If the house is going into foreclosure, the sale is going to occur because the payments aren't being made. If your mother isn't prepared to pay off the arrears such that the mortgage is again in good standing, I'm not sure what "say" you would expect her to have. We would have no way of knowing if your father is actually trying to sell the house or at what price.

It is quite obvious that, whatever the inconvenience to you, you should go to the house, find and remove any items of value that belong to you. Otherwise they are apt to end up sold with the home or located and sold by your father. Often when hoarders are involved, the disposal crews hired to clear out the home don't even try to find valuables - everything goes into dumpsters.

If you believe you have grounds to have your father committed somewhere against his will for mental health treatment, you can explore your options; it is very difficult to compel somebody to get mental health treatment unless they're willing to go (and cost is also an issue). You've given us no indication that your father is suicidal or is a threat to the safety of others.