I would assume that he was going into the coffee shop as well. And if he was, that means the handicapped mother would have to return to the vehicle before they left.
I drive my grandma around all the time and will do my best to drop her off at the door of wherever she is going regardless of how close a parking spot is, especially in winter.
I will then do my best to park in a location close to the building so my grandma can safely return to the vehicle without having to walk too far.
So long as you can prove you were staying at the coffee shop with your mother and she was going to return to the vehicle after you were finished at the shop then take your mother as a witness to court and this will be an easy offense to beat by just being honest.
Just because the driver is not disabled doesn't mean they don't have a right to use the disabled parking pass if a passenger is disabled.
This just sounds like an aggressive and uncompassionate parking officer especially considering they weren't even interested in seeing if you were telling the truth.
It would have taken less than 5 minutes to go in the coffee shop have you identify who your mother is and have you stand outside the building and the parking officer go up to the mother and ask who she is waiting for.
If she says her son then boom the charge is garbage.
But if she says shes waiting for someone other than her son and the son was in fact just dropping her off then the charge is good.
Sounds like just a lazy parking officer who didn't want to do a quick investigation that would have saved a lot of time and now this will go to court and waste lots of people's time.
Sigh-