I would offer a refund (but only AFTER she returns the pillows), and would offer to pay for the shipping. If she does not agree, it means she actually likes the items ;-)
The neutral feedback is discouraging, but not the end of the world, particularly since you have a lot of positive feedbacks. The potential buyers do understand that you cannot please all the people all the time, some people just cannot be pleased.
I just wonder if neutral/negative feedback affects you relevancy in searches though. Does anybody know?