She may have died at the address given on the death certificate but perhaps it wasn't a residence , maybe a nursing home or she was visiting someone.
I would look in Herne Bay Kent, re newspaper articles
Bromley & West Kent Mercury dated 31 December 1937.
Miss Josephine Ellen Galatea Yencken of Herne Bay Kent and formerly of Glebe Road Bromley who died last June left ...........
12 February 1938 Herne Bay Press
Notice re the estate of Miss Josephine Ellen Galatea Yencken late of W ? Tree Cottage Greenhill Gardens, Herne Bay Kent. ......
26 January 1935 Herne Bay Press
City council approves bungalow Greenhill Gardens for Miss Josephine Ellen Galatea Yencken being handled by solicitors.............
I don't have a subscription to Find My Past hence the ............... as I can only see the first line and not the remainder of the article.