Frank, Ruth & Ruth's mother

Something that’s always disturbed me is what I imagine to be the relationship between Frank, Ruth, and Ruth’s mother. What I mean is surely Ruth’s mother heard -- perhaps even witnessed -- the beatings, but likely didn’t intervene. I’m sure it broke her heart too, but, given the times, she probably elected not to involve herself. I wonder too how much Ruth and her mother talked about the abuse, if at all.