You are lucky that you're mom is very active. We just return with my MIL, just 74, but she has lived a very sedate life and it shown. It was very difficult for her since she does not walk at all, so we took her in a wheelchair and that was just much better. Even so, she stayed at the hotel's room a couple of times since she was so exhausted. I'm not sure she enjoyed the parks very much, we are a very active family and love to walk, so that put a lot of stress sometimes.
The worst part of all is that I'm not sure what she did enjoy

since she said that everything was great, but I think she didn't want to let us down.
Anyway, you still might want to think in the WC in case she does gets tired, or if she needs help with the lines, sometimes just standing there may be too tiring.