I wouldn't suggest "maybe Hans Christofferson Bengard." ..... Since the 1920 census in Cass Co, MN says that Pauliine was born in MN, but Johanna & Hans were born in SD, Then the Bengards must have lived in SD, then moved to MN by the time Pauline was 20. While in SD Alfred Christofferson probably got to know her and went to MN to marry Pauline and bring her back to Kingsbury Co.
In further research(esp 1900 census), it may help to know just when Pauline celebrated her birthday. Since the 1920 census says she was 20, it conflicts with other sources that say she was born 1902. ..... As far as Pauline's mother, in 1927 and 1939, she was listed in the Brainerd, MN phone book. She may have died there about 1939, since I couldn't find her in the 1940 census.
Someone has a family tree on MyTrees.com for your Bengard family. Is that you? or someone you know?
If you google "Bengaard, Brainerd, MN" you can find a link to the obit for Arthur Bliss, naming his mother "Hannah Bengaard" This is probably Pauline's 1/2 sister Johannah.
Hope this all helps.
Bill Feller