Hi James-I can totally relate to where you are emotionally with your mother because something similar happened with my own mom.
This is what I call a typical case of people running their 'Death Urge'. The DUrge is the subconscious desire to die permeating peoples actions and running the present moment to a large degree. What I call putrifaction in the present. You are witnessing it right before your very eyes and it is soooo disturbing because these people are sooo veiled. You are seeing them without filters because you are choosing life rather than hopelessness and despair...some of the ingredients of the DUrge.
Maybe you can find an ally at the place where she is being treated? Some one symptahetic?
I don't have an answer but I am sending you my support.