Hey there, Elaine!
Renting a scooter or ECV while at Disney is is very easy!
Every theme park and Disney Springs has
ECV rentals at the park entrance. They are available on a first come, first serve basis for $50/day plus a $20 deposit that will be returned to you when you return the ECV for the day. My husband rented one during my daughter's first Disney visit, and it was a magical experience for my husband. It made enjoying the parks so much more special.
Renting the ECV from the theme parks or Disney Springs requires that guests return it before leaving the park. If you grandmother is in need of an ECV to help her get around the resort hotel and theme parks, you maybe interesting in renting from a local distributor who can also deliver and pick-up the ECV at your Walt Disney World Resort. Each retailer will charge a fee, just be sure to check their website for the most up-to-date information.
With the help of the ECV, your grandmother's visit to Disney will be even more magical!
If you need more planning assistance before your trip, please with the Disney Parks Moms Panel!
Wishing you pixie-dusted planning and a magical time!
Korliss