Any new program should be approved and cleared by their physician. All clients should be instructed in how to move all of the joints in as full a range of motion as they can without injury. In the case of the foot/ankle, the toes can be flexed/extended and spread and the ankle can be taken through plantar/dorsiflexion, eversion/inversion, and cricumduction. This is where you could start and build from there. As long as the person has no wounds on the feet, I would also incorporate aquatic exercise. Myofascial release is a possibility, but all of these should be cleared through their physician.
the one thing I had good success with is the MELT Foot treatment. I have witnessed as people with very poos sensation in their feet were regaining some feeling as a result of this systematic application of balls for the sole of the feet.