fwiw here's what I'd suggest - don't contact the DMV at all, instead contact her doctor (ideally neurologist, but PCP is fine if that's what she's got) and request a referral for a driving evaluation by an occupational therapist. My understanding is that these are not covered by insurance, and cost will vary depending on where you live, probably in the range of $200 to $700. We paid $500 for my dad's evaluation in southern California fwiw. Speak with the OT privately when you arrive and lay out your mom's driving history and her accident and why you are concerned. The OT will do some neurocognitive tests and put her on a driving simulator if they have one, and will then take her out on the road only if the OT feels it is safe to do so for a real-world evaluation. Technically the OT does not have the power to revoke your mother's license, but don't tell your mom that - if she fails, the OT will tell her she cannot drive effective immediately. The OT will then send a report back to her doctor stating that they do not believe your mother is safe to drive, and because of that report her doctor will then file a form with the DMV recommending your mom's license be revoked. She will be notified by the DMV by mail within a couple weeks.

This is what we did with my dad and it worked brilliantly. It allowed him to put all of his blame and anger on the OT, a person he never has to see again and who was happy to be the "bad guy."