Hi,
Welcome to RootsChat

I wonder if Isabella/Annie went to live with her daughter Alice Daisy EVANS.
Isabella/Annie is on the 1939 register as Isabella so she is using that name then.
I found these deaths,
Isabella EVANS Dec Q 1951 Carmarthen 8a 265
Age: 77
and later,
Alice Daisy EVANS Dec 1980 Carmarthen 24 1687
DOB: 15 Nov 1899
Age: 81
so maybe this is something to look into

Regards,
Daisy