I am not sure this is the information you are seeking or not.

The Western Australia Electoral Roll has the following.
1936 and 1937
HEARN, William George Wills. A labourer.
At Mt Palmer via Yellowdine
HEARN Mary Ann
At Same address .
If this is she, this may be her death.
HEARN Mary A
Female
At Yilgarn
Reg 24 Year 1940
William continues registration in the general area, but no others with him to 1954.
Sue