I am hoping this link will work for those interested. A very kind person was able to track down the final resting place of Margaret Jardine McLeod Montgomery in Matapedia cemetery. Strangely, I've still never been able to find any information about the death of her husband Major Montgomery. No obituary, no death or burial records, not a single mention of him after the 1891 census.
She is buried with her son John McLeod and grandsons D. Howard Montgomery and Major Chesley Montgomery. The fourth side of the grave marker is blank.
If anyone has any leads on my ancestor Major Montgomery, I'd love to hear!