Dad died 10 years ago and Mum started serious drinking to forget. She can drink a bottle whiskey in a night and will have a drink at any hour of the day or night. She knows she drinks too much and often comments (usually after a fall) that she must stop, but she is an alcoholic and can't stop. She has very painful ostio-arthritis and says she uses alcohol to deaden the pain and to help her sleep.
She is an adult with all her marbles in place and I am struggling with caring for her and not controlling her life.
I ask also what the living arrangement is, as that could make a difference in her loneliness.
Assuming you're in close proximity to her, I would (a) try to get her to attend AA meetings (b) try to engage her in activities she used to do before her husband died (c) try to get her involved in more social activities so she doesn't feel so lonely (d) take her to lunch, for walks, to a museum...places that will help soothe and calm her.
Redirect her attention so she doesn't feel so isolated and turn to alcohol for comfort.
And try to get her to eat celery. It contains COX-2 inhibitors and may help mute some of the osteoarthritis pain. I eat a whole head of celery daily and feel the discomfort in my joints if I don't.
Is everything being done for managing her pain medically. No one should have to live in pain day after day, and if there are some things that would lessen the pain without increasing her risk of falling that would (in my opinion) be a better solution. Then she could have a moderate amount of alcohol to enjoy it, not to deaden the pain.
But if she is an alcoholic, do-it-yourself ways to quite or even to significantly reduce the amount may pose risks of their own. Offer to get her help to cut down on her drinking if that is what she wants. If it isn't what she wants, I'm not sure you can force the issue.
My heart goes out to you. I honestly don't know what I would do in your situation.
My mother thinks I'm anti-booze: actually I'm not, I weaned her off treble brandies at night because they were screwing up her sleep patterns, that's all. But if she'd been drinking that hard, for that long, I don't think I'd try to tackle this on my own. First port of call - discuss this with your mother's doctor, if you're able to, or with your own if not. The point being that you COULD just stop buying it for her but you might create more, and worse, problems than you solve. Tread carefully.
What pain relief does she have for her osteoarthritis, besides the alcohol? - which, by the way, will not be doing her joints or her bone density any favours.
Also, I don't mean to split hairs, but there is a difference between alcoholism and - what would you call it - a late-acquired habit. How certain are you of the alcoholism diagnosis? Did she drink a lot before she was bereaved?
As I say, if it were me I'd put all the issues in front of a doctor, make sure s/he was paying attention, listen to his/her advice, and take it from there.
I really hope you get somewhere. A dear neighbour of mine - a sweet woman - came to a sad end in circumstances very similar-sounding to your mother's, and I would hate it to happen to anyone else. Please update.