Marg, the times she was in the hospital without drinking, she knew she had a problem. It was her choice to drink again when she got out, instead of seeking help. I'm really sorry that her son had to see how she died. But there's really nothing you could have done.
I do want to mention that the meanness may have been partially due to hepatic encephalopathy. The ammonia levels get high in the brain and cause behavior changes such as becoming nasty, confused, forgetful, and antagonistic.
The best thing you can do is to quit drinking so you don't follow in her footsteps. She couldn't be a good example, but she can certainly be a horrible warning.
Hugs,
Connie