Ryerson has some death notices which may be Nellie (especially given John's death was registered in Wyong and Earlwood is now the name of the suburb that used to inclde Canterbury)
Nellie Eileen LEE   late of Killarney Vale, formerly of Earlwood   
died 13 Jan 1983
Death Notice in 
Sydney Morning Herald   14 JAN 1983   
Obituary in 
Wyong Advocate 26 JAN 1983
Ryerson may be able to give a transcription but others on Rootschat may have access to the notices.
http://ryersonindex.net/search.phpThis is the only death for a Nellie LEE on NSW BMDs for 1983
1983 #100796   
Nellie Eileen  LEE   Father: William - no mother listed, no place of death registration listed.      
Judith