I have a legal question about how to file charges on a person who has commited assult. the police refused file?

I was wondering if there is anyone in the legal system that could give a bit of advice. My mom lives with her boyfriend in her house. her boy friend has another house that he used to live in before he met my mother. Now his son and daughter stay where he used to live. my mom and her boy friend share a car. one day my mom went to her boyfriend's old house where his kids live to pick him up. My mom has always had problems with his daughter. she has attacked my mom in the past on many occasions. his daughter is in her 20's my mom is 58. Is daughter is also mentally ill but refuses treatment. mom's boyfriend invites her in and his daughter attacks her and bends her thumb back as if to break it. my mom wants to call the police but his daughter wont let her. instead she calls. my mom is arrested for knowingly entering the dwelling of his daughter and yelling obscenity's in an unreasonable manor as to disturb the peace. when my mom asks the police to arrest her bf's daughter for assault police refuse. Her boyfriends daughter has a criminal record and isn't allowed to be alone with her own child. my mom has no record what so ever. what can she do to bring charges against his daughter? should she try to talk to the police again or is there someone else that she can go to to get charges filed? she lives in a small town where she is likely to have the same officer who refused to file charges respond if she calls the police. If there is anyone who knows the law well that could help me out with this, appreciated. Also the state that this happened in is illinois if that helps. thanks.