Both my husband and I celebrated our birthdays at WDW in November (they're two days apart). The emphasis was on his, as his age ends in a zero this year.
We stayed concierge at the Animal Kingdom Lodge and did the Sunrise Safari one morning. At the Tusker House breakfast, they gave us each a piece of birthday cake. The safari and breakfast were wonderful.
There was also a birthday cake in our room when we returned on the day between our birthdays. Yummy!
This was an adult trip, so we did the Segway Tour at Epcot on another morning. That was especially fun and special, and added to the celebration atmosphere of our week.
I asked a friend of ours, who lives in Florida, to surprise him on his actual birthday. We were watching a parade at the Magic Kingdom, and up walked our friend! That was very cool, and he joined us for dinner that evening at Narcoossee's. We sat at a table by the window and watched Wishes. I had arranged for the restaurant to bring a birthday cake and special dessert tray to our table after dinner. Very wonderful. Sigh.... Later that evening we went to Pleasure Island and did a little club hopping.
We both wore birthday buttons on our birthdays (each park gives them out free) and it was really nice to be wished a Happy Birthday all day long.
There are many wonderful ways to celebrate a birthday at WDW. Think about what your mom might enjoy and what your budget can handle - all sorts of things are possible!
Have fun!