Take pictures of the place, the parking spot, get the name/address of the towing company then call up some morning radio show like q94 or b103 to whine about it. With enough bad press, the towing company may back down.

The tow truck wasn't likely just driving around. They were probably called by someone at the front desk of the retirement home. If not, someone at the front desk should have asked them not to tow (which they can do).