I could tell by the way niece spoke over the phone, she was very hesitant and seemed embarrassed.
My mother sometimes made me ask people for things that made me very uncomfortable. I still cringe thinking about these incidents. The fact that your niece was embarrassed means there's a good chance she will not turn out like her mother.
I agree with others that it would be best to find a physical thing (not money) that the niece could use. I do some crafts, and when my niece excitedly told me she was redecorating, I made her some unique items that matched her color scheme and theme exactly. She was thrilled.