Shes on the 1911 as Sophia Louisa Mongan. Living on Independant means with sister Elizabeth Ann Down. They had a servant named Sarah Willis. Annie wasnt there.
Address: 6 Ellison Terrace, Ellison Rd, Streatham.
Your Sophia has been very helpful!!! As she was widdowed she didnt need to put her marriage/children details but she did. She stated she had one child who had died by 1911, no children remaining. (Her sister had 7 children, all still living in 1911).
They also gave detailed info on their home: 3 sitting rooms, 5 bedrooms, 1 kitchen. (They would have been told not to include listing a bathroom.)