Hi
While you are waiting for an authoritative answer!
May was buried in Te Awamutu. The cemetery database (and probate record) seems to suggest that she was living in Putaruru.
Where did she die? Don't know, but I am getting the impression from some stuff online that the funeral director was often the informant on death certificates in NZ. Maybe that has something to do with it?
Whatever, the Births and Deaths Registration Act 1951 does say
6. (1) Subject to the provisions of this Act, all births
and deaths occurring in New Zealand shall be registered
by the Registrar whose office is nearest to the place
where the birth occurred or to the place of burial, as
the case may be.
Provided that any other Registrar may register any
birth or death if it is shown to his satisfaction that
the person whose duty it is to give the information
required by this Act for the registration of a birth or
a death could not, without difficulty, delay, or expense,
attend at the aforesaid office.
Peruse it here
http://nzlii.org/nz/legis/hist_act/badra19511951n22328/Ian