You could ask her about her mother. Talk about fond memories.

Losing your mother is hard. This year it will be 5 years for me.

Letting her talk about her might be a good emotional outlet. It might make her cry more, but that isn’t a bad thing.

It always hurts to talk about. But I do feel better when I can share a bit of her life.

You need to have that kind of friendship where it wouldn’t be strange. If you only nod to each other at the lunch table, then perhaps just leave it.