I am so sorry for the loss of your mother. I was in the same exact place as you are but I talked with my father before his operation. I was just a little over 6 months sober. He was so proud of me. He didn't know how or why I decided to stop. He was worried about his going in for an operation and my drinking. As we waited for the operation he would ask how I was. I told him "don't worry...I am fine...I will be fine...drinking is the last thing that I would do" He was happy. My father made it through the operation but died 4 days later. I am so glad that I am sober. All of the things that my sister and I have to do are hard enough sober! The reason that I am telling your this is because my father was worried that I may relapse because of everything that was happening. Your mother would be exactly the same...don't drink...she is proud of you. My dad was 82 also. It's only been 2 1/2 months.
My prayers are with you and your family.