Tom, your great-grandmother was Elizbeth Mc Mullin - is that her maiden name or married name?
If it is her maiden name then her father would be John Mc Mullin. I did a search of the BC Archives Death Registration Index located at: http://www.bcarchives.gov.bc.ca/textual/governmt/vstats/v_ev...
and I found the following two that hopefully will be of some help.
Name: JOHN HUGH MCMULLIN
Event Date: 1943 5 11 (Yr/Mo/Day)
Event Place: OAK BAY
Reg. Number: 1943-09-624548
B.C. Archives Microfilm Number: B13179
GSU Microfilm Number: 1953639
Name: JOHN JAMES MCMULLIN
Event Date: 1960 1 29 (Yr/Mo/Day)
Event Place: PRINCE RUPERT
Reg. Number: 1960-09-002627
B.C. Archives Microfilm Number: B13245
GSU Microfilm Number: 2033302
I did the search by entering Mullin for the surname and telling it to search as a partial match so that it would bring up all McMullins and MacMullins (just in case).
The date period of these indexes are 1872-1980.