No matter what, even in the buildings with the elevator, you still have stairs to the second floor of the unit. Unless you are giving mom the master bedroom, she will still be climbing stairs.
Also, remember that all(except one) GVs start on the second floor of the buildings they are in. You have to walk up one flight of stairs to get to the first floor of the GV. The master is the only bedroom on the first floor.
Even the handicap accessable GVs really aren't....unless the handicap person gets the master bedroom. There are no elevators to the second floor.
I would also think that the new buildings are often requested, making it less likely that you will get one without claiming 'medical reasons' and even with that, there are only a couple GVs in the new bldgs and unless someone is checking out the day you arrive, you may have difficulty even getting a medical request honored.