In 1881 she was with her large family at Stodmarsh Court, Nr Canterbury, though Ernest and Ellen were away.  She was 50 and born in Adisham, Kent.

In 1901 she was living at Dunmon, Elms Road, Ealing, Mx with two daughters, a son and a grandson and with one servant; she was 70 and born in Adisham, Kent.
_________________________________________________________

Regarding her surname, the marriage was presumably before 1855, the birth year of their first (surv.) child.  There is only one David Collard marriage on FreeBMD before 1855 and it is in Dec 1850 in Faversham, but the page number is unreadable, though I reckon it is on page 319.

I then searched for all people married at Faversham in Q4 of 1850 and there was an Emily Collard on p. 319 with no husband to link with.  I wonder if she was merely known as Ellen?  And might this have been a marriage of cousins?

A further complication to this is that there was another David Collard who married in the early 1850s as he and his wife Catherine had children starting in 1852, from the 1871 census for Garrington House Farm.  In 1861 however, he was a widower at Garrington House farm with three or four children.  In Dec 1861, there was a probable marriage between David Collard and Catherine Weekes and it looks like they had four daughters.  So the David and Emily marriage of 1850 must have been this David’s and there is still no record of any marriage between David Collard of Reculver and Stodmarsh Court and any Ellen.

In the 1861 census, the youngest child of David (widower of Garrington) and Emily Collard was Agnes aged 3 and born in 1858.  So her mother died after that, making her the death on the indices of Emily Collard in Q3 of 1859, Bridge dist, vol 2a, p. 371.
_________________________________________

There is only one clear candidate for her death on FreeBMD between 1901 and 1935:

Q2 of 1912, aged 81, at Brentford dist, vol 3a, p. 134

And Ealing, her residence is 1901 is in the Brentford district.
________________________________