Family #20 in the 1775 Grimm census.
Family #57 in the 1798 Grimm census.
Family #138 in the 1834 Grimm census.
Maria Katarina Fritz was born in 1769 to Johannes Fritz and Anna Margaretha Thiel Pikus in the village of Grimm, Russia. Originally from Baden-Durlach in what is now Germany, her parents immigrated first to Denmark, and three or four years later to Grimm, Russia.
In 1767 her brother Jakob was born. Anna Maria's birth followed two years later in 1769. Their youngest sister, Henrietta, was born in 1772. There is mention of another sister who was born in 1772 named Anna Margaretha. She was clearly omitted from the 1772 census by name, unless Henrietta and Anna Margaretha were the same person. If they are not the same person, then they would have been twins, or perhaps one born at the beginning of the year and the other born at the end of the same year. It makes no sense, however, for a surviving three-year-old to not be living with her family at the time of a census.
In 1773 or 1774, Maria' Katarina's father passed away. Her mother soon remarried Christian Pikus. In the 1775 census, she is listed as the stepchild of Christian Pikus.
1775 Grimm Census 
By 1798, she had married Heinrich Rudolph and the couple and their children lived with her mother, step-father and younger sister Anna Margaretha.
1798 Grimm Census 
She is not specifically listed in the 1834 census, but her husband and children are. Her husband Heinrich Rudolph is listed without his wife in family #138, however, he is not designated as a widower or widowed. Divorce was frowned upon in the Volga German community, and it happened rarely. Her husband continued to live in his father-in-law's household. Would that have happened if he and his wife divorced? It may have, especially if their divorce came after Christian Pikus' death.
It is equally possible that she had simply passed away. Her youngest child was 25 (born in 1809), and it's unlikely that her husband would have remained unmarried if she had passed away in 1809 from a death related to that son's childbirth. But if she passed away in the early 1820s, it's possible that the census taker saw no reason to note that her husband was a widower in the 1834 census. The family's entry in the 1834 census is shown below.
1834 Grimm Census 
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