This is a very long shot but I'm wondering if this could be her death, with a very strange transcription of "THURSTON" and with the wrong forename for the father? (this transcription is from Ancestry so could well have mistakes.) I'm looking at this one as the index entry for the marriage of Mary Ann to William BROWN gives her father's name as William THURSTON.
Victoria, 1895, #9627
Mary Ann BROWN, 61
Death Place: Horsham, Victoria
Father's Name: Thorston Chris
Estimated Birth Year: abt 1834
My thoughts as to the name changes - but only guesses - are that her mother had at least two partners and thus changed her name a couple of times, so that Mary Ann also used a couple of different surnames.
Judith