Unfair

I have a friend of mine whose mom has raised her first 2 kids from babies. Her mom told the kids that she and my friend's dad were their parents. Recently, my friend told her daughter that she is her real mom. Her daughter doesn't believe her, and it's tearing her apart. My friend's mom also showed her daughter "pictures" of her coming home from the hospital to cover up her lies. Also, we found out that since my friend's mom had all girls, she wanted a boy very badly. So she started a fight with my friend and took her son. I can't stand to see my friend hurt like this. I think her mom is crazy. What should she do???