1. It’s possible the Sarah Smith in this census is the same person...

From the 1900 US Census, Illinois, Logan, West Lincoln - 4th Ward, ED 43, 1403 4th Street, Enumerated 13 Jun 1900, Sheet 22B, Lines 84 - 87:

Sarah Smith; Head; Born Mar 1861; Age 39; Single; POB Illinois; Father POB Illinois; Mother POB Illinois; Occupation - Housekeeper; Owns Home.
John Comstock; Boarder; Born Feb 1848; Age 52; Widowed; POB Kentucky; Father POB Virginia; Mother POB Virginia; Occupation - Ditcher; [Owns Home is marked, but crossed out].
Elmer Comstock; Boarder; Born Mar 1885; Age 15; Single; POB Illinois; Father POB Kentucky; Mother POB Illinois; Attends School.
Eva Comstock; Boarder; Born Apr 1889; Age 11; Single; POB Illinois; Father POB Kentucky; Mother POB Illinois; Attends School.

2. Info from a post dated June 1999 to the Ancestry.com message board by Wendell A. Smith indicated Sarah A. Smith may have married a John Smith. [517]

3. Illinois Statewide Marriage Index (1763–1900) shows a John D. Smith married to a Sarah Jane Smith on 11 Mar 1883 in Williamson County. I have no proof this is the same Sarah Smith.