I don't help people to receive gratitude, but I sure as hell do judge when they don't show it. Oh yes I said it, I judge when they don't show it and I can't help but wonder where are their manners?? That's pretty sad that she couldn't even say thank you not even once. And the grandma saying 'good for you'?? What a joke.
Once a couple years ago in my daughter's class a letter was sent home about a boy's mom who was going to have surgery and would be unable to cook dinners for a while. So the letter was asking for parents to donate dinners for a month. I volunteered and had pizzas and sodas delivered to the family. This was a family of 6 or 7 by the way so it wasn't cheap. Never got a thank you note, email, nothing. I'm assuming neither did any of the other parents.
Sorry but having a disability or injury is not a free pass to be without manners. I'm sure these are the same people who want to be treated equally or no different than others. I do think some of them feel entitled or become numb to all the help they receive, just like this mom probably has someone driving her child every year so she's come to expect it.
So to answer your question I probably would've resigned from being their personal driver well before the year was over. I'd also remind my daughter to always get my permission before volunteering me for anything. Although her heart was in the right place, it would've been awkward if you had to say no for some reason.
Also it doesn't matter if we don't know all the details, it only takes a second to say the words 'thank you' or to type out a quick email, or to have your husband make a quick call and say it for you, or write a short note. Really no effort at all. There's no excuse for no manners.