Could this be her other son who didn't go to Oz? ["Children 3 male, 2 female"]
1881 census:
James LYNCH Head M Male 54 Ireland Fireman
Mary A.S. LYNCH Wife M Female 53 Douglas, Isle of Man, England Fireman Wife
Alexander LYNCH Son U Male 23 Douglas, Isle of Man, England
Elizabeth E. LYNCH Daur U Female 18 Douglas, Isle of Man, England Dressmaker
Source Information:
Dwelling 13 Queen St
Census Place Onchan, Isle of Man, Isle of Man
Family History Library Film 1342346
Public Records Office Reference RG11
Piece / Folio 5603 / 66
Page Number 24

Married Mary Ann Finigan 1848?

Sue