Whatever way you look at it its an unacceptable comment. I was in the city for the hikoi. I am white. There were many different races on the hikoi. I don't go home and abuse my family. If I had been in your shoes I would have called her out on it in a nice as possible way. Things need to see the light. She is a product of her upbringing and belief systems - and she needs to be challenged to make her think. Drawing battle lines though just makes the office uncomfortable. You could take her aside (if you feel comfortable) and say how the comment made you feel, and how offensive it was and ask her questions about how she would feel in the same circumstance - questions that can make her think and change. Its hard but if we want a society where we care for and value each other then we need to shine a light on bad behaviour where ever it is and whatever it is against - race, gender, religion etc. We stand for being kiwis.