Our community has services that will get senior citizens to the nearest bus stop (you only need to call them). Not saying that is the answer but maybe do some research to see what is available in her area? Ocassionally senior drivers do cause accidents (putting themselves at risk) so it was a good practice for the cop to take the precaution that he did.
PS Though not safer for the senior--some of them around here trade in their cars for golf carts. There is an assisted living facility across the creek from me, one female senior (looks 90) rides her 3 wheeled bicycle with a big basket across the creek to grocery shop......