At least she sought out professional advice and acted on it. It could be a lot worse.

"Sounds like your mother is obsessed with control and worry."

To reiterate: she works at a prison.

She may have simply been fed propaganda about D&D and, due to being misinformed on the subject, expressed what was to her reasonable concern.

Worrying about one thing makes her "obsessed" with it? Nothing about what I read implied obsession.

That pretty much describes anyone who works in a correctional setting.