Can I access Tsumago by car?

I'm planning a road trip with my parents as my mother can't stand or walk for long (15 minutes maximum). Can we drive to Tsumago?

Yes, it is a normal village with normal roads.
I think the only road you cannot drive on is the central road, so a bit of walking is needed to see Tsumago itself. With being able to walk only about 15 min, you might want to look into bringing a wheelchair along to your trip through Japan for the sightseeing.

Enjoy your trip through Japan!