Buy a voucher for her to spend on a handbag. Men can not choose handbags, it's not that we're not capable, it's simply that we're not capable. Apparently.
Ding ding we have a winner.
That's probably the best solution to this problem.
None. Tell your niece that it's time to go shopping for her present. You take her with you and let her choose what she wants and buy it for her.