Hi Teresa,
You may want to add Falkirk to the address - this will narrow any future searches down by quite a bit.
West Bridge Street is right in the centre of Falkirk.
I've had a look in the published pre-1855 Monunumental Inscriptions book, but couldn't find either John or Mary listed in any of the local Churchyards. No doubt they'll be buried in one of them, but if there was no stone, then there's not really any way of finding them.
The Churchyards are: Falkirk Churchyard, Falkirk West Churchyard, Erskine (or Silver Row) Churchyard and the Tattie Kirkyard. (The Erskine Churchyard has now been completely built over and although the other 3 still exist, there's very few stones in any of them)
1. - Falkirk Parish Churchyard
2. - Falkirk West Churchyard
3. - Erskine (Silver Row) Churchyard
4. - Tattie Kirkyard
Anne