Have to spend time with Mom and we just had a disagreement about family and our living arrangements. What do we talk about?

Mom and I had a bit of a disagreement last night and much of it was about my brother and his view of the world and that everyone is against him. She defended him to me (and to the rest of the family through me.) But the disagreement was also over her going out with him and not staying in touch with family and my worry while they were not responding to calls and texts for a few hours. I'm sure Mom felt the reality that her independence has decreased and didn't like that. She can't just "stay out all night" and whatever as she could before her stroke. We both said some things about her living with us that we probably both wish we hadn't said.

While we have made up and asked and given forgiveness, I have to take her to therapy tonight and then grocery shopping. I'm worried I won't have anything to talk about, since this other thing is still heavy on my mind. And she normally has little to talk about since she sits in her room all day and watches tv. Any suggestions?