The reverse marriage entry shows that Jane Rorke was born Cavan, which I believe is a county in Ireland.
I better rewrite that in case the copyright editor deletes it before you read it

Thomas Hebbard DAWSON married Jane RORKE 1870 in Victoria
Reg number: 3487 His birthplace shown as Penzance.
They do not appear to have had any children in Victoria up to 1888. May have gone interstate right away - or even to New Zealand.
A marriage nor death not found for Ann up to 1888. There is a death in 1898 -
for an Ann DAWSON, parents unknown, aged 46, Kew Lunatic Asylum #12564
Cannot know if she is yours without the death certificate - she may be a married woman, from a different birthplace.
But it appears that they went elsewhere - interstate or New Zealand - no death for Thomas to 1901.
Christine