I think Mary Mason Menzies died in England. Needs further research and confirmation, but potentially at least sons William and David made their lives in Lancashire after their marriages.
So we have the death of David Snr in 1889. Looks likely that this is from when Mary, mother, left for England at some point (added, after 1891 with John's 1891 census entry for her).
1901 entry in Dalton in Furness, Ulverston
David Menzies 74 b. Scotland
Matilda Menzies 65 b. Scotland
Alexander L Menzies 25 b. Dalton-in-Furness
Margaret Menzies 33 b. Dalton-in-Furness
Mary Menzies 96 Mother b. Chatham, Kent ??
Death notices appeared for her in a number of papers. See clip below from Witney Gazette and West Oxfordshire Advertiser, 19 March 1904. Another one mentioned that her husband had passed away some years at the age of 101 (close enough!).
Added: The Manchester Courier, 15 March 1904, states she was born on 14 March 1805 in Wigtown. Maybe correct birth date, just wrong place. All her Scottish census entries showed Ireland as her birth place.