Rebecca:
Port Orleans: Riverside is vast, and you are thoughtful to research where best to stay in light of your mom's mobility issues.The
Royal Rooms in Oak Manor (Building 90) and Parterre Place (Building 95) that overlook the Sassagoula River are less than a 5-minute walk from both the Main building where the food court is located as well as
Boatwright's. Disney bus transportation has several stops at the resort and you're less than 5 minutes from two stops. (I'd recommend using the one behind the buildings near the parking lot.) Although there are several quiet pools located throughout the resort--and one right between these two buildings that offer the Royal/River rooms--the "kiddie" pool is located on Ol' Man Island in the middle of the resort. My children still talk about the pool area from our stay there.
If you want the southern feel of this resort but with a smaller footprint, you may want to consider
Port Orleans: French Quarter. While the Royal Rooms with river views are slightly closer to the lobby, there is not a table service restaurant at the resort. However, the resort is serviced by a boat to Downtown Disney. The pool and kiddie pool are not stellar in my book but you can visit the one at Ol' Man Island at its sister resort. There is only one bus stop at PFQ which I liked when I stayed there. For a quiet stay, I recommend PFQ but if you're looking for more activities, Riverside fits the bill.
Wishing y'all a magical vacation!
Whitney