How do I keep my mother from renewing her license?

My mother is 82. She had a stroke a few months ago. While she is doing extremely well considering, her executive functioning isn't what it was. My dad has been driving her around since the stroke, but she is going to take the written test to renew her license in a few months. On the form, she lied about having had a stroke.

I don't think she'll pass the test anyway, but if she does, what can I do to prevent her from being able to renew her license? She wasn't a great driver before the stroke, and now it terrifies me to think of her being back on the road.

UPDATE: I spoke with her medical group and they are requesting an evaluation from her primary care doctor. They will say a family member is concerned. I am also going to send the form to the DMV requesting additional evaluations.

Thank you all for your advice! This has been weighing on me, so I feel so much better knowing what actions to take.