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The parents might have been buried in the same cemetery as Leon. I'd contact the cemetery.
You can do a Google search for Los Angeles County California Cemeteries and look for her in the inventoried cemeteries.
Sometimes where a person was buried will be in their obituary. There is a volunteer who will lookup Los Angeles obits. You'll find his/her contact info at www.gengathering.com. You must create a user ID and password to enter this web site. However, access to the volunteer info is free.
You can use the same process to find where Bessie was buried.
There isn't a volunteer who looks up obits in San Bernardino Co. Successful Searching!