My mother died 8 years after being diagnosed with Alzheimer's. She had not attended in years, and by the time she died I hadn't either. I never got the opportunity to talk with her about my decision to leave this religion, but I know she would never shun me.
i decided not to have a formal memorial for her because I knew that I wouldn't be able to tolerate all those witnesses. So I invited my freinds and family to my home and let it be known that any from our former congregation would be welcomed. Since I'm not disfellowshipped, there were a few witnesses and elders who came. I asked a former close freind who was an elder to speak briefly and to make it personal and warm. So we made alot of food and had a wonderful time. I know that may sound strange but because of the informal setting and lack of ritual we could concentrate on my mother as a person, not as another cog in the wheel.