Was Elizabeth roughly about 16 years younger than William as I have found an entry on the Aberdeen and North east Scotland Family History site, under the Index to Monumental Inscriptions that could be a possibility.
The names given for stone number 113 in Alvah, Banff (booklet reference AA108 from ANESFHS) are as follows:
Annie Murray - 26 May 1873
William Murray - 18 June 1885
William Murray - 29 March 1893
Alexander Begg Murray - 13 November 1904
Jessie Murray - 22 March 1910
John Murray - 12 Jun 1925
Elizabeth Runcie - 12 Oct 1931
A quick check of Scotland's People shows an Elizabeth Runcie, other name Murray, born 1843 aged 88 dies in Banff, Banff in 1931.
Here's the link to the Aberdeen and North east Scotland Family History site
http://www.abdnet.co.uk/mi-index/Lynn
