I relate to your determination to be a good daughter.
You write: "Now she wont go anywhere and in one month is so bad I cant begin to describe. He has rented a place and is leaving this weekend- what do I do? I love her and don’t think that just giving up or in to this disease is the answer. If you love the person and don’t want to lose them how can you give up on them? She was so close a few months ago – I need some advice other than to walk away."
I suspect her drinking has escalated with your father preparing to move out and the situation is still too new and volatile to make any kind of real intervention.
If I were in your shoes, I would drop in to see her once a day, make sure she is alive and has groceries. Keep the contact brief and positive and don't discuss her drinking. I would make my visits as stable, positive and predictable as possible, and probably early in the day. I would have this as a working plan for say the next month, and then reevaluate.
And then find Adult Child/Alanon for yourself so that you don't lose your own life in dealing with this. We can end up in much worse shape than our drinking mothers.