But your suggestions presume that her parents actually bothered to think about what could happen to their princess when they were not at home, then bothered to think of how their princess could protect herself with or without firearms or other weapons, and then bothered to teach their princess and then bothered to make her practice.
Yeah, I'm being harsh. But then so's the world out there. Avoiding BGs has many similarities to getting out of the house during a fire or other disaster involving the structure. For those who have not made plans and taught them to everybody living in the home (adults as well as children) this is as good an excuse to start now as any you could want.