From what I understand, the house is heavily mortgaged and has no real value to them. The house is going to be lost whether he files or not. They are not a wealthy family so I don't think there will be a whole lot of non-exempt property.
As for his physical and mental ability to attend this "meeting" (this is the first I've heard of a meeting of creditors) I think the answer is YES. However, his psychological state, even before the death, is questionable. He seems very alert at times, then looses his sense of urgency and stops caring to think about difficult things. I don't think this is neurological. He is a relatively well-spoken man.
As the other attorneys have observed, someone who has social security as their only income and most exempt property, there is very little that creditors can do to collect the debts. They can her an attorney and file lawsuits, but collecting would be nearly impossible.
Nonetheless, some people will file bankruptcy just to get rid of the debt-related stress.
Finally, you father might have some form of dementia. it might be necessary to have a court appointed guardian to help him with the bankruptcy.