Well... it's really hard to force an alcoholic into treatment. In most cases the addict has to be willing to get help. On the other hand your mom shouldnt be suffering this at all. You guys could get help on your own from Al-Anon, Al-Anon is help to the addict's families.
On the other hand, you *CAN* pressure the alcoholic intro treatment. For example my parents told me it was either treatment or the street. If I really wanted to continue partying I would have chosen the street, but I was a big ***** (I'm sorry for the wording) to even try it, so I did go to treatment, and as time went by I changed my mind about using drugs/alcohol.
It's hard, it's really had, I can understand your pain, something that I went through, but from the addicts side. It's still really painful from the addict's side, probabbly comparable to the families. It's a disease that we don't want to accept. With this I just want you to understand him, but this doesn't justify it.
Best of luck, and my prayers are going to your family.