Hiya
My Kathleen died in Tottenham in Nov 1957 aged 83/84.
I have just re-checked those census and here were my glitches:
Kathleen C Smith b.Buckhurst Hill still lived at home in 1901 as she appears on the census with her parents. My Kathleen was married and on the census as Holmes.
Isabella Smith who lived in Nelson Road in 1901 at number 4 as a widow - I found her in 1891 with her husband George at a different address in a Ponders End and with same sons Harry and James.
Unless I am missing something I think this rules them both out???
Rgds
Sam