Mons Knudsen died 27 Sep 1898 and is buried in Swan Lake Township Cemetery, Maple Hill, Emmet county, Iowa. His birth year would be ca. 1832.
His wife, Jane, is buried there also. The record says she was born 22 Mar 1847 and died 29 Mar 1930.
An online tree says her name is "Gertrud Jane Halstensdatter Braatole", and that she was born in Voss, Norway.
Looking at the birth records for Voss, I find:
Born 22 Mar 1847
Father: Halsten Steffensen Braathole
Mother: Britha (?) Sjursdatter
Kildeinformasjon: Hordaland fylke, Voss, Ministerialbok nr. A 13 (1836-1851), Fødte og døpte 1847, side 133.
Permanent sidelenke: http://www.arkivverket.no/URN:kb_read?idx_kildeid=11773&...
From the information you have given, this does appear to be the wife of your Mons Knudsen. Their first son, Sever, was born ca. 1869 in Wisconsin.