Hi, Erica!
What a great group you have heading to Walt Disney World!
Glad you sent your dates so that I could avoid suggesting a location that is scheduled for refurbishment.
With a party of 14 heading to WDW in May, you may want to book a dinner at Magic Kingdom's newest establishment,
Be Our Guest Restaurant. The detail infused throughout the entire structure is spectacular, the menu exceptionally well-designed, and your entire family will feel as if you've stepped into the Beast's Castle you remember from the film
Beauty and the Beast. One look at photos of the restaurant, or a glance at the
menu of Be Our Guest Restaurant and you'll see that Grandma will feel extra spoiled celebrating her 80th birthday in such a special place (as she should be!)
Because your parents are Disney Vacation Club Members, suggest that they look into purchasing the Tables in Wonderland Card; a one-year Membership is available to DVC Members for $100. This entitles the TIC Member to a "20% discount (excluding tax and gratuity) on all food and beverages at participating Resort hotel and Theme park restaurants." This discount applies to the Cardholder and up to 9 additional Guests, mostly at Table-Service locations; with a party of your size, you might save $100 the very first time you use it.
If you're on the Dining Plan, this location will use only 1 Table-Service credit, too.
Feel free to send more questions either regarding additional options, the resort you'll be staying in, any DVC-related questions and more. (...maybe a birthday cake delivery, perhaps a special surprise in Grandma's room...so many options for this special lady!) I'd love to help!