There are about 450 death entries in the index from 1911 when she was last see to 1951 when she would have been93.  I cannot identify which was hers.  Assuming she wished to be buried with her husband, this reduces the number of Mary E Walkers to 17, still not clear enough.

In 1939 there were a mere three candidates in Yorkshire and 20 miles around, two had been married:

Name           DoB           Address                            Marr Status  Occupation
Mary E Walker  10 Aug 1858   Bridge House, Swainsby, Stokesley  Widowed      Private means
Mary E Walker  28 Aug 1858   17 Crowlees Rd, Mirfield W. Yorks  Married      Housewife

The second of these could have remarried but it is unlikely that she would have remarried another Walker.

So, if this Mary survived to 1939, the first entry could well be her at a possibly upright eighty-one.  If so, when did she die?  One death is found after 1939 that was registered not far away in Cleveland:

Name           Birth  Death  Registration
Mary E Walker  1859   1941   Cleveland, Yorks

So I had a look at her probate and she appointed her housekeeper as attorney which seems unlikely.

Then I started by searching the probate index for all ‘Mary Elizabeth Walkers’ on FindMyPast which showed probates for fourteen such (only) with immediate links to the probate index content and which included this entry:

Name                     Death  Probate  Location
Walker  Mary Elizabeth   1921   1922     Yorkshire, England.

And the details had the full name of her husband as executor.
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Her probate index:

1921
372 - Folio number
WALKER Mary Elizabeth of Uplands Ben Rhydding Ilkley Yorkshire (wife of Walter Arthur Griffin Walker) died 11 March 1921 at Mentone France  Probate London 22 February to the said Walter Arthur Griffin Walker merchant.  Effects £1021 10s. 1d.
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Their marriage index:

First name(s)     Walter Arthur O
Last name         Walker
Marriage quarter  2
Marriage year     1881
MarriageFinde     Walter Arthur O Walker married one of these people
                  Mary Elizabeth Conyers
District          Wharfedale
County            Yorkshire
Country           England
Volume            9A
Page number       272
Record set        England & Wales Marriages 1837-2005
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