Xiao Baitu, a question about last address in China

My hu*****and was a student and lived in the university before coming to USA. His HU Kou has been eliminated by the university when he graduated and he put his files in the university. So how will he fill in the last address in China (living more than one year)? If he writes his parents' home address, how to explain he has no HU KOu there? Or he needs to write the university's address?
Thank you.