What an incredibly difficult situation!

I did some digging and found some sites that might offer some help. I hope you're able to find a solution.
https://www.dementiacarecentral.com/caregiverinfo/driving-problems/
Covers legal stuff, but also has tips like Transportation Options
https://yourdementiatherapist.com/alzheimers-dementia/caregiving/driving/
Also offers Alternatives to Driving.
https://alzfdn.org/driving-and-dementia/
More info, including this helpful resource:
"AFA’s dementia-trained social workers answer questions about driving very often. Contact AFA’s Helpline at 866-232-8484 or click the chat icon in the lower right hand corner of this page."