Is there a tax break or grant that will help in the purchase of a car for transportation of the elderly?

I don't know of anything specific for elders, but you might consider trading it in on a larger used car. It doesn't have to be new as long as it runs well & is safe. Consider looking on the internet sites like craigslist -

The papers carried a story about an incentive to buy newer cars, but as I understand it the catch is that your old car has to get less than 16 miles per gallon to qualify