Oh, I wasn't expecting to find them together in 1939. Harriet is recorded here as ten years older than you suggested!
https://www.ancestry.co.uk/interacti...d014ad687aa2c5
That should be correct as the dob fits wth her death reg in the year you suggested:
Name: Harriet Williams
Death Age: 97
Birth Date: 8 Dec 1875
Registration Date: Jul 1973
[Aug 1973]
[Sep 1973]
Registration Quarter: Jul-Aug-Sep
Registration district: Wrexham
Inferred County: Denbighshire
Volume: 8a
Page: 1868