Mystery solved! The newspaper from the date that Sophia died is not available on Winona Newspaper Project, but the one 25 years later is. The address listed in the article is where Friedericke was living with her 2nd husband in the 1900 census.
Winona Republican-Herald, 27 Oct 1924
Twenty-Five Years Ago
Mrs. Sophia Bentz passed away at her home, 402 East King street, yesterday afternoon at the age of ninety-two.
Also found a death record on familysearch for Friedericke, that lists her father's last name (close match) and her mother's first (Sophia) and maiden name. So that was definitely her mother.