Yes, that was exactly what I was worried about. Not so much being impaired, because she is disabled and frankly, would not be able to assist in an emergency. I did tell my husband last night and feel much better. Its something we can deal with together now, instead of it being a huge secret on my ownYou don't think your daughter is going to say something to your husband about her grandmother's smoking or at the very least the funny smell in her house?
Life isn't black and white, this might be the perfect opportunity to start a discussion with your daughter about that. The first thing though is to have a conversation with your husband. As far as forbidding your daughter to go there, does your opinion not count for anything? Your daughter is at an age where she doesn't need your mother to provide hands on care so how would she be endangering your daughter? I assume she isn't driving her anywhere.
I have issues with anyone being judgmental about someone doing something to ease pain that doesn't differently affect others.
I'd be more concerned about my mom not being emotionally stable and the impact of that on my child. Although that would be a teaching moment as well.