Is the person cleared to work with you? Do you have any recommendations from their healthcare providers? If you are ready to go, start small and adjust to what you observe and the client tells you. Let the clients reaction to every progression guide you.
I would start with ROM movements without added weight. Arm/Upper body movements can be done sitting down (as necessary). Sitting down and standing up is very useful. A variety of leg motions can be done with hand support on the walker, a chair, ect. (make sure it is stable). Be sure to cue the client very clearly. Try not to talk too much while they are doing the exercises.
Be cautious, everyone is different and will react according to how they function and respond.