The reason why you had a hard time find the marriage is that the given names were different.

Odilon Amyot, son of Benjamin and Domithilde Blanchard, married Délima Pilon, daughter of Joseph and D. Yon, 07/07/1873 in Clarence Creek.

Here is the civil record, from the Archives of Ontario:

011441-73 Odile AMIOTTE, 26, Farmer, St. Augustin, Clarence, s/o Benjamin AMIOTTE & Domathilde BOUCHARD; married Delina Pilon, 18, Thurso, Clarence, d/o Joseph Pilon & Marceline YON; wit Benjamin AMIOTTE, Clarence & Xavier Pilon, North Plantagenet, 7 Jul 1873, Clarence Creek

A Joséphine Pilon, daughter of Joseph and Marceline Dionne, was baptised in Buckingham (Papineau county, Québec) in 1854 (I do not have the exact date). This is clearly the right person (Yon and Dionne were interchangeable surnames).
Unfortunately, the 1852 Census for Buckingham township is unavailable.

B definitely stands for "blanc", meaning white.