No Martha Pierce Douglas was born 31st July 1858, in Egham and Baptised 28th Sept 1858 also Egham
She died 12th jul 1900, so was only aged 41 at death.
Her late husband was 12 years older (she was his third wife)
Probate was by James Douglas her oldest surving sibling, who was living in Torquay, and aged 63.
So Matilda is not Martha.
Also Leamington Spa Courier 21st July 1900
Deaths ...
STANLEY- On the 12th July, at Llandudno, Martha Pierce, widow of John Edward Stanley, of the Crown Hotel, Leamington, and King's Head, Wellesbourne, aged 41.