Xavier

I find that the last few hours of a fast are always the most challenging. I have come to rely on prayer during these times and I also focus on serving, but as you've mentioned, during a lockdown is kind of hard! 
Perhaps, document your thoughts and/or testimony for your children/family in form of a video log! I am actually doing that right now and it's definitely keeping my mind off of things!

The way I saw it is that he gave us a definite way for a proper fast, but IF for some reason, you are not able to do it, then there is a way to still "fast" by giving up something you might consider a sacrifice. 
so, to summarize, 
1.- Abstain from eating and drinking for a period of 24 hours
or
2.- Giving up something you would consider a sacrifice to go without for the same period
Of course, every fast is accompanied by a monetary donation of your choice... perhaps that's a sacrifice on its own.

The way I saw it is that he gave us a definite way for a proper fast, but IF for some reason, you are not able to do it, then there is a way to still "fast" by giving up something you might consider a sacrifice. 
so, to summarize, 
1.- Abstain from eating and drinking for a period of 24 hours
or
2.- Giving up something you would consider a sacrifice to go without for the same period
Of course, every fast is accompanied by a monetary donation of your choice... perhaps that's a sacrifice on its own.

I feel like including an extra sacrifice cannot hurt. I am feeling closer than usual to the divine today because of the fast. 

I believe that the book of Job gives insight into how God works with men. As Elder McConkie said, "Job is for people who like the book of Job."
I do not believe that God and Satan casually chat, as the highly formulaic retelling in Job might suggest. I don't believe that Satan goes before God to request permission to afflict people, and that God then grants that permission. I do not believe that Satan creates life or manipulates non-human life to afflict mankind. Insofar as the book of Job suggests otherwise, it's clear that the book of Job is speaking figuratively or in allusion or as a fable.
Job may well have been an actual man, and the trials that he faced in the book might well reflect actual trials faced by a real Job (and perhaps by the rest of us). But to use that to draw the conclusion that Satan bargains with God to afflict mankind is as absurd as using the Biblical account of the sun standing still during Joshua's defeat of the Amorites to draw the conclusion that the sun circles the earth.

March Madness has been cancelled!
Yup, Satan is involved.

Which then begs the question, how do you know the adversary can not or has not received permission with this either? The point being Satan was given permission and did create boils.

It's funny.  All of a sudden I'm no longer the kooky guy in the office.  People are now asking me for advice.

He has FAR more power than we probably give him credit for.  He has power over the waters, or so it was believed by many in Joseph Smith's time.  The Bible relates that he had the power to replicate some of the miracles of Moses including snakes, blood, and a few others.
There is ALSO a war that is still going on.  Many think that the War in Heaven ended when 1/3 of the host of heaven were cast out of the presence of our Father, but as we can see in Genesis, the Adversary is still here on this world.  He has been given some authority and power to control things.  He has not been given the power to directly take over bodies or flat out destroy them, but he can influence things to harm or eventually cause death.  This is an ongoing war and he has the worst of intentions for all of those who opposed him previously.
I would not be surprised if many of the evils such as viruses and sicknesses were created by him to plague and torment mankind.  He hates us and wishes ill.  He can only do so because he is allowed to do so (and a prime example is Job, where he was allowed to do such things, or the story of Moses and Pharoah's sorcerers), but I think he's allowed greater variance than some think in that arena as well.  He, as we are, is still a child of our Father and as such still has some gifts that are granted unto him until the final day of judgment.
In this, there is an ongoing war and he is the enemy.  I feel he uses all the weapons at his disposal to harm or hurt.  His first goal is to make us miserable and if he can do so by making us fall from grace, he will.  Then, if he can kill us before we can repent or gain grace again, he would probably try if allowed.  If he can kill those who will refuse to turn and who will stay faithful...he probably would try if allowed.  He is an enemy and as such, he is going to do all in his power to destroy us one way or the other.
Fortunately, we have the Lord.  The Atonement ensures that even if the adversary harms us, even if for a little while, by causing us to leave this mortal coil or to suffer in this life, that eventually he will be crushed.  Unless WE CHOOSE to allow him to make such misery permanent, he can have no power to do so.  He can cause us temporary misery, but by accepting the sacrifice and atonement of Jesus Christ and repenting and allowing the Lord's power to guide us and direct us, we can triumph over the adversary.  He may be able to harm us and hurt us, but through Jesus Christ we know he will be destroyed in the end and cast into outer darkness.

"So went Satan forth from the presence of the Lord, and smote Job with asore bboils from the sole of his foot unto his crown."
Seems like scriptures potentially present a different theory.
Remember, the creation of this earth was accomplished by individuals without a body.

I'm am prepping by following the council of the Brethren, as always.

I blame Bush. No, wait, I mean Trump.

the glory of male is indeed female. I'll post more on this, all three points.

So, I have read most of the responses here and they all seem to be helpful, however, they sound speculative in nature. No-one here can make any types of assessments as to whether or not your son has a "mental illness". Does he display symptoms that could lead one to believe that he is depressed, sure! But I am not going to diagnose it because I am not trained NOR have I spoken to him in person. 
I can share with you what my own experience was and then you can decide if my experience and what I did is something your son could do as an alternative. he needs help or if this is a passing thought.
Firstly, I commend you for wanting your son to be whole and healthy and happy, like any loving and caring mother would. Missionary service is a really wonderful and rewarding experience one that gives back even days, weeks, years later. However, it's not easy to re-adjust once the mission is finished.
A missionary Elder (or Sister) is endowed with the power of God himself to preach and touch the hearts of those they come in-contact with. That power can be felt and it is ever present in a missionary's life (so long as he/she is following the commandments and mission rules). With that power, a missionary can see how the Gospel, when being taught by the spirit, changes lives and blesses those who accept the message of salvation. Once the missionary is released, the Endowment he had for two years is no longer there and in most cases, not having it is a real feeling of "loss" and can be challenging to overcome. Most missionaries have a well established support system and even then, they struggle. However, if the missionary is focused on his future, He(she) must be involved and active in anything that gives them purpose. But I m sure you already knew that because that's the normal reaction for anyone going through some sort of grief process. 
I remember thinking to myself about how much I longed for my Grandma and my Aunts to hear the gospel and pray to God about its veracity. I then had a special experience about four months after I had started my mission and although at the moment it was very scary, later I realized that it was my Grandma coming to say goodbye. I remember doing my personal study (missionaries have a strict schedule to follow every morning and one of the hours prior to leaving the apartment for the day is to study the scriptures) and while I was reading my scriptures, I felt a sens of deep sadness. The kind of sadness that makes one sob uncontrollably. My companion saw me and was concerned and I couldn't explain what was happening. Suddenly I realized that perhaps my mom had passed away. Soon after I had that thought, I offered a prayer and asked Heavenly Father to help me accept His will regardless of whatever had happened. A few weeks later it as mother's day and I was praying that my mother would answer the call. After I dialed the number it rung a few times and then I heard my mother's voice. I was so relieved and at the same point confused. After a few minutes and greetings she had informed me that my Grandma had passed away. At that moment I felt at peace and I knew that she had come to say goodbye to me. I prayed to Heavenly Father that I needed Him to send missionaries to her right away because I was going to do her Temple Work as soon as I was back at home. Soon after I came home, I went to the temple and id the work for my Grandma and it was a wonderful experience. I have no doubt that she accepted the ordinances and is happy with her decision.  
I am not sure as to why you aren't a member of the Church or if you are but not active, nevertheless, I can see your son wanting desperately to share the gospel with you the way a missionary does and if you have resisted to learn more about the Gospel before, he might be having an internal struggle because he wants the Best for you. If you at some point decide to take the discussions, please involve him in the process. I am going to be bold and say this, it will be a much better experience of you at least learn and take the discussions now, than after you're gone through the veil. Eventually, if you decide not to take the discussions now, he will do the work for you after you're there. However, please do now that whether you do it now or then, you still have a choice and regardless of how your son feels or your husband, you are loved by God. 
Another aspect about being a returned missionary, is the fact that usually the bishop of your Ward puts the young man to work (a calling in the ward) and he might want to take a few weeks to "re-charge".
Regardless of whatever the reason is, do not dismiss your gut-feeling and keep the lines of communication opened. He needs to talk to your husband, and he needs to talk to his bishop. He needs to get active and go to school or get a job. 
One last thing, upon finishing a mission, the mission president does one last interview and in that interview, most times, the mission president extorts the missionary to find a young lady to marry and not to take too long in doing so. It is a good advise however, it is definitely something that could be intimidating.
Hope this helps and gives you an idea as to what he might have gone through. 
To finish, I would like to share with you AND YOUR SON, my testimony: I know without a shadow of a doubt that your son was called of God and that he had God's blessing to testify on His behalf. I know that the gospel is true and it's real. I know that the Book of Mormon changes lives and I know that it is the true word of God. I know that Jesus Christ is the Son of God and that He is the head of His Church. I also know that God lives and loves His children. He has living angels and some of those are called "Missionaries"! Most of the future is uncertain, but I know that if we live by the Word of God, that uncertainty will turn into Happiness. In the Book of Mormon there is a verse that gives me hope for the future: Mosiah 2:41
I share this with you in the name of Jesus Christ, amen.

Oh ye of little faith!

You sure? I thought that baptizing tens of thousands on my mission meant they did have to listen to and believe me.

In contrast, I could not disagree more. The so-called #MeToo movement is a lie, an attempt to use actual violence and evils done to women as a ram to effect political gain by making women (specifically feminists) literally unaccountable for any accusation they care to make.

I understand that Paul was using the customs of the day as a metaphor to make a spiritual point. Metaphorically, this chapter is about the relationship of the Church and members (the woman), and the husband (Christ). It also provides a pattern for practical religious observance according to the customs of the people of the day, and so it has a literal parallel to an extent, but I think that was his secondary aim.
Our modern prophets give us counsel about the marriage covenant and family relationships, and continue to emphasize the relationship between the Church, her members, and Christ.
The light shineth in darkness. A woman's negative attitude toward men, Christ, the Church, etc. can be overcome with good examples from male and female members of the Church, and cultivating the light of Christ within herself. The Lord is constantly reaching out to her, so hopefully she will be enticed to truth more than to error.

Q: Though very limited, how were his 4x emails toward the end of his mission? Upbeat & positive? Depressed & negative? I would imagine if you were to go back and reread those 4x emails, you may be surprised at what you might notice now.
Q: What reason did he give for extending his mission?
Q: May seem odd, but did he ever make mention of a 'special' girl OR 'extra special' family on his mission?

1) When one goes from having 100% of their time used up in good work to having all their time free, it creates a void.  The available opportunities can seem unworthy (by comparison), leading one to doing nothing, which creates unhappiness while at the same time being addictive.  He needs good things to do - or even "not bad" things, so he doesn't get in the habit of emptiness and idleness.
2) If something bad did happen, he needs to feel safe before he'll be able to reveal it to you (or someone) and work through it.  You need to figure out how to help him feel safe, like he's loved and accepted no matter what.
IMO, going from mission to never attending church is indicative of a problem.  Withdrawing from family is indicative of a problem (unless said family are already dysfunctional or he feels it's not safe to open up to them).  This casts doubt on his reasons for extending his mission - was it to stay for a wrong reason?  Was it to avoid coming home to a situation that makes him uncomfortable?  Or....?
I'd say some honest and loving conversations are in order where you or his father or someone else he trusts mostly just listens.

What @Xavier seems to be suggesting is that Paul said that a woman's glory is the hair of her own head, while a man's glory is not his head (Jesus Christ), but woman. It's an interesting interpretation, worth thinking about, whether or not you decide there's anything to it.

......
..............
........I'm not sure that's true.

I love the response of Winston Churchill to a feminists that declared that by the year 2000 the world would be ruled by women.  He looked back and uttered just one word - "Still?"
 
The Traveler

Short answer...
No, it is not dead
Longer answer...
...though PART of it still being on earth could be debatable.
It depends on WHICH part you are considering.
One portion would be in consideration to the Line of Joseph and the Patriarch of the Church.  It appears that for now, this idea of the Patriarch of the Church has been taken from the Earth for now.  We are left with the lower Patriarchs, each with a similar authority of the Church Patriarch, but not as encompassing as the responsibility that he used to have.
In addition, it would appear that in some arenas the doctrine taught by the Lord and his apostles in the New Testament has been forgotten, forgone, or taken away.  We see this reflected in some individuals conversations in regards to the Temple Ordinances to a degree.  I'm not really going to touch upon such things here other than to admit that these types of conversations take place regarding some changes in thought and approach within the Church.  Why this occurred, I do not know.  It could be that some favors or ideas in relation to us have also been taken away.
Why, I'm not sure.
Sometimes things are taken away due to wickedness, but as I stated, I am unsure of the exact reasons for what has occurred above.
However, as many have stated, the things of heaven are Eternal and unchanging principles, not things that die on the whim of men.
The Patriarchal order itself in the practice of the family is still the proper order instituted by the Lord regardless of what happens in the world.  It is still found in the Scriptures and can still be practiced in the Home.  In this, it is not that the father commands nor demands obedience, but that he leads the home with love.  It is more akin to how Captain America and the Avengers team up (Comic Books), or Frodo and Sam (Lord of the Rings), or Joseph and Hyrum Smith.  One is typically the Leader, but the tasks they take on are normally more of a co-equal job in which they tackle things together and cooperate and converse with each other on how they will do things.  Sometimes it is not the leader that is the one that makes decisions, and sometimes it is the leader who needs support rather than taking charge.  In almost all instances, it is a companionship that strengthens each other through cooperation rather than a dictatorship of authority.
In this, as the Father is there to lead the home, but NOT be a dictator over it.  Leadership is not dictatorship and normally those who are dictators are not really very good leaders.  Good Leaders listen to those they lead and try to inspire them to follow them.  It is a matter of inspiration and encouragement rather than one of dictatorship and force.
Something else to consider, that may be dying, but not dead yet, or in better words, slowly fading from the Church but not taken away from it yet, is that of the Patriarchal Order in the Priesthood.  There are some here that would disagree with what I am about to discuss.
This Order is the highest one in the Priesthood.  To obtain this Priesthood authority, it CANNOT be held solely by a Man.  It is ENTERED JOINTLY by him and his spouse.  In this way, his wife ALSO holds the Priesthood.  Through this order of the Priesthood in the past, women have been able to call down the powers of their husbands priesthood in blessings and other things as seen in Church History.  They are JOINT holders of this Priesthood authority.  The natural order of this leads to the Man being the Priesthood Holder in the Home.  He is the one who leads in the Priesthood.  The ONLY instances (that I know of) when I wife called down upon the priesthood of her husband was when he was absolutely unavailable and normally other priesthood holders would be unable to help her in that instance.  It does NOT mean she leads or becomes the priesthood holder in the home, but if church history is an example, that she can bless her children and home in his stead if he is absent.  Though this is no longer really something we practice, it can be seen as having been done in church history.  It indicates that this is a JOINT power, but also emphasizes the proper order and leadership of it in the home.  Without one, the other cannot possess it.  A MAN CAN ONLY have this Priesthood authority and enter into this order if they are Sealed together in an eternal union.  Without a spouse, the husband loses this authority. 
To be clear, it is NOT a separate Priesthood, but a Priesthood authority, or natural order from the Priesthood.  It is still the Melchizedek Priesthood, but a higher manifestation of it.  It is the more complete manifestation of it rather than a separate grouping.
This particular order of the Priesthood is the Highest there is, encompassing all others within it.  It is under this authority that men act as a representative of the Lord in their homes, and in their absence the mother also has equal hold.  This helps them to lead their children in righteousness, and guides them to bind their children to them both spiritually and eternally.
This has not been taken from the earth or the church (that I know of) yet.  It may be in the future with the way things are going (I don't know the future), but currently, it is STILL here.
Thus, in this way the Patriarchal order is still among us for our present time, in my understanding.