A 72 yr old is not being taking care of by her drunk husband and bipolar daughter. How does the son get POA to make decisions?

An adoptive daughter and the husband of a 72 year old elderly person is always fighting (verbally and physically) and putting the elderly in physical danger. They already broke her shoulder after she had a stroke several weeks before and now she do not have any use of the hand on the side that her shoulder was broken. The daughter is not on her medication for bipolar and the husband is drinking almost 20 hours a day. The elderly person is not getting fed or bath on a regular occasion and now has a rash that is being treated with an antibiotic. Her birth son who also lives in the household wants to help her but because she has a husband it is difficult to make the decisions for his mother who also has signs of dementia. He is being told that his mother has to ask for help but that is extremely difficult because the husband does not let her speak for herself.

Between the daughter who was recently on house arrest and the husband who is drunk most of the day on hard liquor makes this extremely difficult and this elderly person will probably not survive the turmoil happening in this household. Her own son have to wait until the husband leaves the house to take care of his own mother e.g. feeding her and helping her get her clothes on for bed.

The husband moved her away from all of her family and now she really only has her son to a least keep eyes wide open on her for her safety. Her son who is in his 57 needs advice on what he can do to protect her from anymore violence in the household but also what he can do to get her taken care of so she can live out the rest of her life in peace.