Cause of his death was Gastritis.
Information on census records appears to indicate that William, Diana and daughter, Susan, immigrated from New York to Canada between 1843-47. The census of 1900 confirms that William and both his parents were born in New York. William came from Canada to Michigan in 1897, and lived with his son, Eli, until his death in 1901. The 1900 US census lists William's birthdate as March 1817, however this date is contradicted by earlier Canadian census records which consistently put his birth year as 1822. I tend to favor the earlier records, as William was more likely the source of this information (info on the later census may have been provided by his son or daughter-in-law).
William married Diana M. in 1842 in Sweden, Monroe County, New York. (Diana M. was born on 22 Jun 1823 in New York, died on 6 Nov 1862 in Tillsonburg, Oxford County, Ontario, Canada and was buried in Nov 1862 in Tillsonburg Pioneer Cemetery, Tillsonburg, Oxford County, Ontario.)
William next married Ellen GILMORE on 11 Oct 1868 in Tillsonburg, Ontario, Canada.1 (Ellen GILMORE was born in 1844 in Oxford County, Ontario, Canada, died on 18 Feb 1893 in Tillsonburg, Ontario, Canada and was buried in Tillsonburg, Ontario, Canada.) The cause of her death was Terminal Illness.
Ontario Marriage Index, 1858-1899 (Oxford County, Ontario, Canada). Surety: 4. Name: William Wilson
Birth Place: Unites States
Estimated Birth Year: 1826
Spouse Name: Ellen Gilmore
Spouse's Age: 24
Spouse Birth Place: Ontario
Spouse Residence: Norwich Township
Spouse Estimated Birth Year: 1844
Marriage Date: 11 Oct 1868
Marriage County: Oxford
Family History Library Microfilm: 1030062
2 1900 US Census (Meridian Township, Ingham County, Michigan). Repository: Ancestry. Surety: 4. Lists Eli Wilson (age 52, b. Canada), wife Sarah (age 52, b. Canada), and Eli's father, William Willson (age 83, b. New York), widower, living in Ingham County, Michigan. Eli is listed as a "farmer." Eli and Sarah indicate that they have been married for 26 years. Sarah indicates that she has had one child, who is still living. William indicates that both his parents were born in New York (the record appears to have been initially written as "unknown" in these boxes, then changed to New York). Eli indicates that he and Sarah immigrated from Canada to Michigan in 1883, and Eli indicates that he was naturalized. William indicates that he immigrated from Canada to Michigan in 1897 and is not naturalized.
3 1851 Canadian Census (Dereham, Oxford County, Ontario, Canada). Repository: Ancestry. Surety: 4. Lists William Willson (age 29, b. U.S.), wife Diana (age 26, b. U.S.), and children Susan (age 7, b. U.S.), Eli (age 4, b. Canada) and Elizabeth (age 2, b. Canada), living in Dereham, Ontario. Also in the household is Elizabeth Willson (age 18, b. Canada), who is likely William's younger sister. William is listed as a "wagonmaker." The family's religion is "Universalist." The ages and birthplaces of Susan and Eli lead us to conclude that the family immigrated from New York to Canada sometime between 1843 and 1847.
4 1861 Canadian Census (Durham, Oxford County, Ontario, Canada). Surety: 4. Lists William Willson (butcher), wife Diana M., and children Susan, Eli B., Eliza J. and Roscoe E, living in Durham, Ontario. Living next door is a John Willson (age 60? b. U.S.) who may be William's father. More research is needed.
5 1871 Canadian Census (District 13, Division 1, Durham Twsp, Oxford County, Ontario, Canada). Repository: Ancestry. Surety: 4. Lists William Willson (butcher), second wife Ellen, and children Eli and Roscoe, living in Durham, Ontario. William indicates his religion is New Connexion Methodist, and the origin of his family is Scotch.
6 1881 Canadian Census (Tillsonburg, Oxford County, Ontario, Canada). Repository: Latter Day Saints Family Search. Surety: 4. Lists William Willson and his wife, Ellen, living in Tillsonburg. Son, Roscoe, married the same year, so no children are in the household.
7 Certificate of Death (Michigan Department of Health, State of Michigan, Ingham County). Surety: 4. Records death of William Wilson [Willson], wagon maker, on 14 May 1901 in Ingham County, Michigan.
8 Brock District Marriage Register (Dereham, Oxford County, Ontario, Canada). Surety: 4. Records marriage Alexander Wilson to Freelon Patricia Tic(?) [apparently illegible] on 19 Mar 1847 in Dereham, Ontario. Witnesses are Alexander's brother, William Wilson, and his wife Diane [sp. Diany] Wilson. The couple was married by Elijah Harris, Methodist Episcopal.
9 Marriage record (North Norwich, Oxford County, Ontario, Canada). Surety: 4. Records marriage of Eli Dennis Wilson, age 24 (born in Tillsonburg, living in Tillsonburg), son of William Wilson and Diana Wilson; to Fanny Edmonds, age 21 (born in Glanford, Ont, living in Norwich), daughter of William Edmonds and Ann Edmonds. Witnesses are Michael Woodword (relationship unknown) of Norwich, and Maggie Edmonds (probably Fanny's sister) of Norwich.
10 Shenston, Early Settlers of Oxford County, Ontario, 1852, 215. Surety: 3. William Willson resided on the north side of Dundas Street in Woodstock, Jan 1836.