The manifest from Ellis Island tells us she came over on ship Stavangerfjord with her mother, both were headed for Christ Lee (son-in-law/brother-in law), 1714 Banks Avenue, Superior, Wis.
Her mother is: Hulda Holst F 52y M Norway, Scandinav. O. Aker, Norway, born in Fredrikstad (town in Østfold).
In Oslo in 1900 lived 3 women who fit this description, but none of them were married to a Holst. Maybe the name/age of Christ Lee's wife (Hulda's daughter) could give some new leads? Do you know the name of Svanhild's father?
327 persons in Oslo are using Holst as a surname or middle name today.