IF she does not receive the package at all, or returns it to you with shipping at her own expense I would offer a partial refund, OR offer a generous (30~50%) discount on a future order.
IF she did actually receive the package, just later than anticipated, and decides to keep it I WOULD NOT offer her a refund because she did get her item, and you did put your time and resources into making it. However, to appease the situation, I would offer her a smaller (10~15%) discount on any future order for her inconvenience.
Since this situation is unfair from both perspectives, a compromise to meet in the middle would be the best course of action, if possible.