On our first family trip to Disney World way back in 2008, we requested Kosher meals. What we got, of course, was prepackaged kosher meals heated up in their plastic wrapping and brought to us in that form. I remember having such a meal at Liberty Tree Tavern (ordered ahead of time) and being able to order at QS places (No advance notice required- had a list of QS with Kosher meal availability.)
Since then, we have opted to eat at Disney like we do at restaurants at home- as vegetarians. We count on restaurant cleanliness and avoid any meat/shellfish/non-kosher-fish (and their by-products). This allowed us to have freshly prepared food. Of course, this won't work for your mom if she is strictly kosher and can't accept food prepared on non-kosher equipment or potentially non-certified ingredients.
Hopefully someone with more recent experience can offer some advice.