familysearch shows a possible death: https://familysearch.org/pal:/MM9.3.1/TH-267-11846-67681-93?cc=1463156 Mary B Anderson, wife of Otto, aged 29 - b. Norway, parents listed as Andrew Johnsen and Ellen J. Olsen. She died and was buried in Concord, MA, in 1906.
Is Jennie O the "Janna Ottilie Andersen" b. 30 Mar 1899and chrs. 11 Jun 1899in Oslo?
I suggest for the daughters that you look to see if you can find probate records or an obituary for Christian Otto. Those records may name them and give you their married names.Also if you know where the father is buried, check the same cemetery in case they were buried there.