She was listed with the family in the 1920 census but she was not listed with the family in the 1930 census.
A Mary Banks married a David Lowe in Aitkin County on 4 April 1930. That couple had a son, David, born 22 Jul 1932 in Aitkin County. That David Lowe was born 10 Mar 1901 and died in Farm Island Twp, Aitkin County, on 31 Mar 1981.
Couldn’t find her in the index of Minnesota deaths.