I agree with Mer. Take comfort in the fact that your Mother is no longer suffering. You probably don't know what happened because your Mother didn't want you to know. Parents don't want to burden their children with such matters. Parents take great joy in watching their children flourish and will shield them from anything that may break their momentum.
Understand that liver disease has numerous causes and so many have nothing to do with drinking. Your Mother would not want you to beat yourself up over this, so please don’t do this to yourself. Honor her wishes and peace be with you. Cherish her memory and know she is smiling upon you. I know you will miss her until you meet again.
(((hugs))) Take care and let us know how you are doing. Our thoughts and prayers are with you.