I can understand the situation, but it's her fault for choosing the path. She should preserve her power and rebel when an opportunity arrives. I didn't have any experience with a stepmother but I stayed one of my relatived house for 7 years for my studies. Their words used to hurt me even if they were good with me at the begining. I stayed quiet for 6 years, thinking that everything would be all right but they didn't appreciath it and in the last year I showed them how terrible I can be using words with a smile. In the 6 years, I figured out their weakness, and I used to trap them with their own statements. I am usually the most polite and obedient person, but messing with me is like playing with fire and I break down anyone mentally if I consider them as my opponent. I protected myself from those things. I am saying so much that because I think you friend can't be saved unless she saves herself. Tell her to be brave for herself. The world is not for cowards. It may sounds harsh but it's the reality.