We absolutely MUST try to talk older people into direct deposit with SS checks and any other regular monies she gets. And she should keep her credit cards and check books in the bank safe deposit if she is afraid of having them stolen. She could have someone (or a bus or taxi) take her to the bank with a prewritten list of who gets what, plus her customer numbers at the top of most invoices, and a handful of pre-addressed letters.
I'm 77 and do my own stuff, but like others have said, I do not let strangers inside my house, talk to them from behind a locked screen door, and when I do bother answering the door I have either a base ball bat or Tiny Tim (a snub nosed revolver) in my hand. I don't get much repeat traffic!
When friends come over they phone first, or else I call them.