I have the newspaper for that date - there was only a brief death notice for Nellie:
"MARKUM, Nellie Lorene, 92, homemaker, Thousand Oaks, died Saturday. Arrangements by Griffin Family Funeral Chapels, Thousand Oaks."
published Wed Feb 23, 2011 page 7B
Perhaps the mortuary can give you more information or even a copy of the death certificate.