That was going to be the next suggestion ... have someone meet her right outside of customs/immigration. That way if there is an issue it can be immediately resolved, and her catching the connection (leave extra time between flights) is pretty much guaranteed.

If she can't walk far as you mentioned above (few airports have C&I a short distance from anything useful and few places to sit once you get there), then go for the wheelchair and tell her to wait for it. She should also remind the FA on the flight that she is supposed to have a chair at landing.