Does my mom have rights to the house that she lived in for 15 years with her boyfriend and the house is only in her boyfriends name

In California, the rights of unmarried couples living together (cohabitation) are different from those of married couples.  Since your mom wasn't married to her boyfriend, she doesn't have automatic rights to the house, even though she lived there for 15 years.  However, there are some legal considerations that might come into play, such as cohabitation agreements or implied contracts. If there was a verbal or written agreement about property sharing, it might be enforceable.  It's best to consult with a family law attorney who can provide specific advice based on the details of the situation.