Each state has their own version of a no contact order. You'll need lots of documentation of harassment (voice recordings help), documentation that you requested no contact, some sort of confirmation that the message was received, and a lawyer in each jurisdiction to help you through the paperwork and court system.
Even then, it's a civil matter, and if you win, it's just a piece of paper. Getting enforcement against a mentally ill elderly relative will be difficult.
I went through similar issues about 10 years ago with a stalker, and both my VA and PA lawyers advised not going through with it. I didn't end up pursuing the court orders, and got resolution through other (legal) means.
Info on VA orders. Info on PA orders. Good luck.