I have heard mother give out her address. A man showed up at her door dressed with an ID and in a power company vehicle, saying her bill was over due and he was there to cut off her power if she didn't give him her credit card to him to pay for it, not a check. Her caregiver, (she has 24/7 care) called me, because I live in a Continuing Care Retirement Community in Florida, she refuses to move here with us. I told her to call power company and the police, yes it was a scam. Mother will not listen to anyone.
Next, contact her bank in writing to let them know she is a vulnerable adult. I don't know that you can get any protections requiring two signatures for her checks since you don't live nearby, but talk to the branch manager about what you can do.
I'd also install a Ring doorbell that you can see when someone comes to the door, and a couple of security cameras on her front door and driveway.
With cell phones, these sort of blocking apps also exist, easy to install and use.