Your father in law just lost everything in his life, you can't expect him to bounce back so fast - everyone copes with loss differently.
He isn't depressed or mentally ill, he is experiencing very normal emotions because of very terrible things that happened in his life.
He should be sad! You would be too. He should feel like never going to work, and if I was in his shoes, I would be sleeping in the house too because it would be the only thing I had left.
There are more important priorities other than money.
When somebody loses everything in their life, they have to go through stages of mourning, and it can be a very transforming process. It's common for them to need to be alone, to accept that they are alone. When you've lost your family, you've lost your house and everything that means anything to you, you realize you don't own anything and never will.
Eventually, losing everything can become a very freeing process where the person will recognize that they don't need anything or anyone to be happy, that happiness comes from within.
At least he is not coping with his sadness and grief through alcoholism or addiction.
Everyone deals with loss in their own ways. In my past I've both experienced wanting to be alone to deal with my loss and wanting to surrounded by people I love during my loss.
He might not want anyone around him and he might not be ready to talk to anyone about how he is feeling and that is okay.
If you are truly worried about him harming himself or comitting suicide, then you need to get him help or spend every second of your day with him until he starts feeling better. When it comes to suicide, you should do everything in your power to help someone you love.
The only reason people commit suicide is because they feel overwhelmed and powerless, you just have to help them find a resolution to the problem.
He may also already know things could get better in the future, but right now he still has to deal with his feelings and his loss and that may take some time.
You can try getting through to him by being supportive. Just be there for him, provide a listening ear, bring him some food.
If my friend or family member was in his situation, I would get him to move in with me until he could get back on his feet, and I'd help him out as much as I could. I'd urge him to take even more time off of his job, or even quit his job, in the end scheme of things, jobs are not more important than our wellbeing, and when someone has just lost everything, it could actually be quite an exciting and positive endeavor to start over anew completely, looking forward to finding a new job, something that he might enjoy doing even more. It's important for someone to look at loss as a transformation, because that's exactly what it is. When you lose everything old, you can invite in the new and most times the new, although change can be scary, can be a lot more amazing than what we had before. Transformation can make someone see the world a lot differently, once he comes through it, he maybe a changed person, his perception may be different, he can start living his life differenty, and make a whole bunch of new changes. The good side of loss when it's something that shakes up the foundation of your life and brings it all crashing to the ground, is that you have the opportunity to start all over again, which can be an amazing thing.
You need to be patient with him. He is old and the devastating experiences he had to endure recently had clouded his judgment.
The best thing to do is have him checked, and make sure me is not a menace to himself and to others.
Make him feel welcome inside your home.