The marriage was 7 Feb 1785, it looks possible that Mary was baptised there in 1762.
William Stone age 74 died 31 Jul 1832 (1758)
Burial 5 Aug 1832
Topsham, City of Exeter, Devon, England
Cemetery: St Margaret Churchyard
Do you know the names of their children, it might help as there are a number of possible records for William in the County on family search.
Colin