I have the same problem. I cannot stay with my mother, yet she demands that I visit, and I have to pay for a hotel each time, then she gets upset I cannot go more often. She lives quite a way away so it's a constant source of upset for me.
I love her dearly and basically I make the effort to see her as much as possible and this is my resolve because otherwise I would regret it when she died.
I do not want her to die, I will miss her. I want to see her, but I don't earn big bucks so cannot go as often as I would like.
It's sad. There is not a thing you can do though for someone with an addiction/habit, I know that from experience, they have to want to change.
I wouldn't prioritise trying to stop her drinking, she likely has the attitude 'well I'm not her much longer so may as well enjoy what time I have than live miserably' and for people with addictions/habits like this it would be miserable without their vice.
I've been told 'your mum needs help' or 'you need to stop your mum drinking' by so many people who think the world is a fairytale with no experience of addiction/habit.
But I know exactly how she feels because I have myself had habits (I prefer this term) like this and know full well that you simply cannot make somebody stop.
My advice is enjoy what time you can with your mum and take the peace of mind that will bring you upon her death. Nothing more, nothing less. Don't punish or hate her for her choice - and it is just that; her choice, and her choice to make.