Looking for Sarah Mitchell Married Morgan Bourke

My mother Mavis Kathleen BOURKE, born 1912, Brunswick, Victoria, Australia. (Married Stanley SILVERWOOD)

Her father William BOURKE, born 1882, Elmore, Victoria, Australia.
Her mother Minnie WHITLOW born 1877, Walhalla, Victoria, Australia.

William's father Matthew Mitchell BOURKE born 1844, Moanmore, Emly, Tipperary, Ireland.

I would like to know about his parents:
Sarah (nee Mitchell) and Morgan Bourke.