Guests are welcome to wear flip flops or other water-safe shoes at the Disney water parks. Shoes are actually a great idea for any guest, as the pavement at the water parks can get quite hot in the sun. If your mom is wearing flip flops, she'll have to take them off and hold them while she's on the slides. As this can be a bit complicated, i usually recommend that guests wear water shoes that are secure on the feet. I personally have had good luck with Lands End water shoes, but there are many brands that work for this.
I assume you want the address of Blizzard Beach for your GPS. If this is the case, you can use:
1500 W Buena Vista Dr
(at Osceola Parkway)
Lake Buena Vista,
FL
32830
However, that's not really an address for mail. If you have correspondence about Blizzard Beach, you should send it to:
Walt Disney World Guest Communications
PO Box 10040
Lake Buena Vista, FL 32830-0040
The e-mail address for Guest Communications is:
wdw.guest.communications@disneyworld.com.
Enjoy your visit to Walt Disney World.