Child Abuse

My daughter befriended a girl in her class. They are both 12. When the friend comes over she tries so hard to please, she asks if she can mop my floors. I took this as a pleasant change from most girls her age. However I now know the mother and this child has attempted suicide and has been hospitalized. She is now on Prozac and sleeping pills. The mother put her daughter on the pills because she didn't want to take them. I have to say she is a sweet normal little girl, except for her mother. She is VERY controlling. She has locked the child out of her house at night to teach her a lesson. The mother has come to my house and tried to scream at me for giving the child a ride home from school because she decided the child would be grounded. Is it legal to lock a 12 year old out of the house? I'm afraid the child will attempt suicide again and she has come to my house to talk to my daughter when she felt she couldn't take her mother any more. Should I contact the social worker? Is that the prudent thing to do or is their some other way to help this child?

If a 2 or 3 year old little girl is made to take showers with her father, is that child abuse? If later, it is discovered that an older sister was molested and raped by the father, but this child has no memories yet, would there be any grounds for abuse in the younger sister's case? Can the mother of the girls be charged for setting the girls up to be abused? What if she had any knowledge of what could happen before setting them up?