Howdy Courtney!!
It would be amazing if she could get the discount for you!! I have wanted to do the same for my parents as they travel with us frequently.
However, the policy is that
Disney Vacation Club Members and their immediate family (living in the same household) are eligible to receive discounts on select new and renewed Walt Disney World Annual and Premium Annual Passes. If you can prove (via your driver's license, etc.) that you reside in the same house as your mom, then you will be able to receive the Disney Vacation Club Member discount. If not, the discount is not currently available.
I do love the perks that come with being a Member of the Disney Vacation Club. Even though you may not be able to take advantage of the Annual Pass discount, I love that your mom is sharing her DVC Membership with you. You are going to love every minute of your vacation in March!!
Please let me know if you need any further information as you continue planning your vacation. If you can tell me where you will be staying, I might be able to share some hidden treasures with you to help maximize your time at your resort. So excited for you!!!
Thanks so much for your question and have a magical day!!