I assume you are talking about Federal income taxes? Did she earn enough to have an obligation to file — yet didn’t do so?
I think she needs a very sophisticated and qualified tax person to help her. So I would search for an “enrolled agent” and at least have one meeting. They are NOT obligated to report her noncompliance!
Use this link: https://enrolledagent.com/find-or-verify-enrolled-agent
But that may not be necessary depending on the amount of taxes owed. Perhaps just a CPA can do the job — IF she has kept records of her income during the years she did not file.
She should start by reading this from HR Block: