You may have it but Jessie's death in 1950 was in Victoria (reg 16604).
Death notice from NLA Trove:
The Argus, Saturday 4 March 1950
PETERSON.-On February 28, Jessie N., who passed away at Moana, Colac. -A loving tribute from her sisters.
Do you need the deaths of her 3 sisters? Or anything on Arthur's parents?