She's not listed in findagrave.com.
Burial info is usually found on/in the obituary or death certificate.
You can request a copy of her obituary from the Napa County Library, countyofnapa.org/Pages/Department.aspx?id=215
Napa County Historical Society, napahistory.org/contact.html who charges a fee.
Contact the County Recorder-Clerk, countyofnapa.org/Pages/Department.aspx?id-4294967365 to order a copy of her death certificate. Successful Searching!