What records have you found to base these names and dates on? Are you sure the family in the 1900 census is the correct one? The birthdate is off on Thos (Thore?) by 10 years there - not unusual but needs to be verified. Also, Hannelie was 118 when she died? If this 1900 census is them and the information given was correct, they immigrated in 1874,(so if we can verify names and dates we might find them in 1865 Norway census) and were married in 1878. Illinois marriages for most counties are searchable for that time frame on familysearch.org and for LaSalle county specifically at www.lscgg.org
This is the most likely match: LaSalle county
cert#35 TORESEN, TOMASON BENSON, HANNAH A. Dec 24, 1877
Also, there is a death index for Illinois available for 1916-1947 on familysearch and ancestry.
This seems to be this family in 1880:https://familysearch.org/pal:/MM9.1.1/MXVC-ZW7
in 1910: https://familysearch.org/pal:/MM9.1.1/MKDB-66P
their marriage date is consistent, as is his immigration date, hers is 9 yrs. earlier.
and in 1920:https://familysearch.org/pal:/MM9.1.1/MJ4N-BHR
the deaths of three children from that family:
and Thore and Hannah's deaths:https://familysearch.org/pal:/MM9.1.1/NQNW-MZHhttps://familysearch.org/pal:/MM9.1.1/N3WM-XRP
I would also speculate that as they lived in LaSalle county that Freished = Friestad - that was and is still a common Norwegian surname there. Again, whatever information you have on Regina Gertrude that might link her definitively to this family would be helpful to post - and you might consider doing it on the La Salle county board (or Cook, if this is not the correct family) and gather as much information as you can there that will make tracing them to Norway much easier. This Thore was likely naturalized in Ottawa, La Salle county and the genealogy guild referenced above has some of those records - might tell you where he was born in Norway, and also has that marriage record on microfilm - though 1878 was when the form changed to include place of birth and parents' names.