call the resort directly. i have a feeling the answer might be "no", howver, as there is no way to tell if the person calling (you) is who they say they are.
if you are not comfortable with cash, you can also purchase a disney gift card at any
disney store (in addition to WDW, it's also good at the DS's,
DCL, DL, & on-line).
another option is to call your CC company, and request that an additional user card be overnighted to her at WDW (good if she is staying at least a few days, & she can use cash for the first 2-3. you will most likely need to pay for overnighting).
else the prepaid CC might be the way to go (normally there is a charge for them tho).
just a suggestion though: my DS does not have a CC in his name either, so i got him an "additional user" card a while back there are often circumstances (car breaking down, short trips with friends, etc) where that card can give a parent incredible peace of mind. even if not for this particular trip, consider getting one for her "just in case".
hth
