From Ancestry.ca

1851 census Williamsburg, Dundas County

HESS
Barbra, b USA, living Matilda Tsp, 74, widow
Peter, b Canada, 22
Rodney, 12
William, 4
Ira, 24
Joseph, 22
Silas, 16
Mary, 14
Children all b Canada.

1861 census Winchester Dundas
HESS
Joseph, farmer, 38, married
Santa Ann, 32, married
Amhurst Hunter, 34
Manly Hess, 4
Allen Hess, 2

All born Upper Canada [Ontario]

1871 census has lot of Hess family living in Matilda Tsp Dundas but no Joseph or any of his children.

1881 census www.familysearch.org

HESS
Joseph, 56, Ont, farmer
Sovila, 50, Ont
Manley, 24, Ont
Allen, 22, Ont
George, 20, Ont
Mahlen, 17, Ont [male]
Asa, 14, Ont
Seaphes, 11, Ont [ male]
Mary M, 9
Harriet E, 5, Ont

1891 census Winchester Dundas
HESS
Manley, 34
Margret, 35
Clifford M, 6
Violet B, 5

Marriage of child/chidren of Joseph Hess & Sevila Ann Hunter. She sometimes is refered to as Mary Hunter.

George Hess, c1863, married Martha E McMillan, 4 Mar 1903, Dundas

Asa Hess, c 1867, married Agnes Barkley, Dundas

Allen Hess, c 1859, married Ella Fetterley, 3 Nov 1885, Dundas

Mohlon Hess, c 1871, married Agnes Edgerton, 16 Feb 1894

Death:
Joseph Abraham, 93 yrs, died 16 Mar 1913, b Williamsburg, farmer, married, s/o Abraham Hess, no mother given, informant: George Hess of Winchester Springs, died of chronic prostatic hypertrophy/chronic cystitis, Winchester, Dundas, Registration # 030958.

Sovila Hess, widow, b 4 Aug 1831 Williamsburg, d/o John L Hunter b Ireland & Mary Duval b Onsbruck Tsp, informant: C Hess of Winchester Springs, son, burial: Maple Ridge, died 6 Feb 1922, Registration # 030777.

Birth: Mary Margaret Hess, b 17 Mar 1872, Stormont County, Joseph Hess & Ann Hunter.
Nothing else found on her.
Nothing found on Harriet.
Nothing found on Seaphes.

1901 and 1911 census on www.automatedgenealogy.com

http://www.islandnet.com/ocfa/search.php
This site is an index of headstones only.
A lot of your Hess family is there. The site will tell you how to contact the cemetery.