Just a small update:
Received Margaret's death certificate by email this morning.
She passed away in Hokitika Mental Hospital on 4th Aug 1947. The undertaker was the informant...sad really..no named father/mother. She was a spinster, and "had secondary dementia some years".
The only new information I have is that she was in NZ for 32 years...so still don't know, and I guess may never know why she was there..will keep digging. Thanks again everyone for your help.

MC