Sounds like a classic hostile work environment. I suspect your daughter is really suffering in such a situation. So sorry. This requires a qualified lawyer to break down all the facts and figure out how to put a stop to this.
This is not formal legal advice.
I am almost speechless about this. Contact a good employment lawyer for advice immediately. This boss' conduct as described is in conflict with a number of employment laws --- and perhaps even criminal and discrimination laws. Good luck.