Gjertrud Negaard - from Norway to MN in 1873

I have been trying to find some information about what happened to Gjertrud Larsdatter Negard and her grandmother Gjertrud Halvorsdatter Negard. They travelled from Trondheim, Norway, May 15,1873 on the ship Tasso. They were travelling to Mankato, Minnesota. In the emigration records they are listed as Gjertrud Negaard, 26. She was born in Rindal on March 6, 1852. Her grandmother is also listed as Gjertrud Negaard. She was 72, and born in 1801. She had a son, John Knudson Negaard who emigrated to Mankato, Minnesota in 1876. (John K. Nergaard). In the 1880 Census he and his family lives in Wergeland Township, Yellow Medicine Co., MN. Can´t find any of the Gertrudes there. Is there anyone who has information about these people?