Wow, Kimberly! You are such a thoughtful and dedicated friend!
Your idea of the Disney Gift Card is the perfect solution to this situation.
To get even more bang out of the surprise, you can go on to
Walt Disney World.com and click "Book Your Vacation"; you won't be committing to anything, just window shopping. Price out when and where you think they
might want to stay, as a suggestion, decide if you're able to add tickets and / or a Disney Dining Plan for them and then print out the quote. (You can adjust dates, resorts and options to suit the budget you had in mind.) Purchase your Disney Gift Card in the amount of the package you put together; yet, you've in no way obligated them to a particular date.
Wrap it all up in an enormous package, with the Disney Gift Card at the bottom of the box, and WOW have you got an impressive gift for a dear friend who has been through a lot.
Best of luck in your noble endeavor! Should you have any additional questions as you build the perfect gift for your friend, please do not hesitate to ask! I'd love to help!