If she’s answered their phone calls and engaged in conversations with them, then it is possible that her phone number has been given out to other scammers as well. The best thing you can do for her is to change her phone number, submit a complaint to the Federal Trade Commission, and then register her number to the National Do Not Call Registry.
If you still don’t think that will help solve the problem, fill out paperwork at her bank to ensure that flags are raised or checks are refused if they are attempted to be cashed by the scammers.