If you loan package called for the borrower to carry insurance and she isn’t, then she is in default. Usually that means that you can actually make her pay for you (the bank) to carry insurance in her place. Call your insurance agent and let them know your position and that you need an insurance quote on the property. Mortgage holder insurance is usually high BUT the borrower is required to pay. Also, get a quote for her to carry home owners as well.
Then you can send her a certified letter informing her that she has 30 days to get insurance (and offer your agent’s quote) or that if it’s not in place, you will get your insurance (quote price) and add it to the monthly payment.
From that point, if she refuses to pay, the she is in default.