Have you found any other leads regarding your g-grandmother Lena Leota Hargrave/Furlong/Anderson/Decker?
About the first of August, I wrote to the Family History Library in Salt Lake City, requesting a lookup of Microfilm #1675641,Marriage records, 1859-1924 [Mendocino County, California] for a marriage of Arthur Furlong and L. Hargrave.
I finally received a response a couple of days ago. I was provided with a copy of a marrige register for Brides, letter H, for Mendocino, for the period of 1893 to 1897. There is a listing for Hargrave, Lena, to A. T. Furlong in 1896. Under "Where Certificates are Recorded", it states:
Book 7, page 373.
If you are interested, the next step would be to request a copy of the marriage certificate from Mendocino County Clerk's office, for a $14 feehttp://www.co.mendocino.ca.us/acr/BDM.htm
you could request a copy from the Family History Library, microfilm number 1675792, Mendocino, California Marriage Licenses, v. 6 (p. 312-400) 1891-1892 Licenses, v. 7-9 (p. 1-370) 1892-1901.
You would use the request form available here:
I have not found any additional information for you.