A court case appeared in the SMH on 17 September, 1935, between William John MAYNE and his son-in-law, James Edward Hosking NICHOLSON.
Ruby Dora NICHOLSON was the executrix of her father, William John MAYNE's Will. SMH Tuesday 30 June 1936 and Friday 20 August 1937.
And according to her mother, Annie MAYNE's death notice in 1954, Ruby was still alive at that time.
I cannot find when her brother James William MAYNE died (however, it was prior to 1954).