A Timberwolf or Deltarunner with Loderunner rear end and 20 inch wheels for lower gear inches for the ease of take off. Also I would use a Nuvinci as a mid-drive configuration and a single freewheel on back for ease of changing gear ratios. The Loderunner rear end I'm referring to is to raise the rear portion of the trike to standard seating level for ease of entry and exit. It also allows for a basket or trunk for them to load up with food. The Loderunner is also an excellent choice. But fairly heavy for the elderly to move around.