How do you deal with an alcoholic parent that's 79?

What can I do to help my mother who is an alcoholic at age 79. My dad who is 83 is trying to take care of her the best he knows how but it is getting more and more difficult and I live 2.5 hours away. They will not move closer to me and I drive their every Saturday to help out as much as I can. My dad keeps getting the beer for her because he is afraid she will go thru withdrawal. She also has dementia. I am lost and don't know what to do. They have no money so I can't even bring someone in to help. Thank you