Hello Darren,
I'm happy that your daughter will be making lasting memories with her grandmother. There is a special relationship between grandparents and their grandchildren that is cherished for a lifetime. You will want to choose a resort that has easy access to the theme parks so that grandmother can rest up during those times when she is not with you. I highly recommend any of the monorail resorts: Disney's Grand Floridian, Disney's Contemporary Resort, or Disney's Polynesian Village Resort. These resorts are closest to the Magic Kingdom where you'll likely be spending a lot of your time.
These resorts also have some excellent restaurants so try and make an Advanced Dining Reservation at one of them so it's easy for grandmother to join the rest of the family for a meal.
If grandmother has mobility issues, you may want to think about renting an Electric Conveyance Vehicle or
ECV so she is able to get around the theme parks without difficulty. At the bottom of the web page, you will also find companies where you can rent the vehicle for your entire trip. They will deliver the ECV to your resort and pick it up at the end of your trip.
Grandmother may also qualify for a Disability Access Service Card or
DAS card which makes it easier for guests who cannot tolerate long waits at attractions.
And don't forget to purchase
Memory Maker. You will want to capture photos of your entire family so your daughter can always remember the trip she took with her grandmother.
Wishing you pixie dusted memories and a magical vacation!
Leanne T.