There was a marriage in 1918 and a death in 1954 in New South Wales that I believe was your Doris.
Registration Number: 8333/1918
Groom's Surname Groom's Given Name: WILLIAMS THOMAS
Bride's Last Name at Time of Marriage Bride's Given Name: GASCOYNE DORIS
District: GLEBE http://www.bdm.nsw.gov.au/cgi-bin/IndexSearch?form=IndexingS...
Registration Number: 16228/1954
Last Name Given name: WILLIAMS DORIS
Parents: GEORGE FREDERICK & FLORENCE EMMA
A death certificate can be ordered online and will name her children.