Gustave Olsen and Laura Larsen

I have found information about Gustave Olsen, Laura Olsen and Henry Halvorsen in the 1900 Census for Asker. I am wondering if Laura Olsen is my grandmother, Laura Larsen. The birthdates for Laura and Henry are accurate but I never heard that she had married Gustave Olsen. Is there any way I can get a marriage record, death record for Gustave, or any other information regarding their lives together. She came to America in 1917 with my father, Henry, and married Thorvald Brustad in Hamilton, NY. We never knew of any other marriage. This is very confusing and I wondered if there would be anyone who could help me trace Gustave Olsen or find records of their marriage. Many thanks.