Mable and Clarence Holladay

I am searching for some information on my great grandparents and I have come to a road block. My grandmother Betty Elizabeth Holladay, married name Castro, has documents that mable and clarence as her parent but I don't have any offering birthdays or any further informaton. Please help.

My grandmother was born in oklahoma in November 2, 1938 to Mable and Clarence Holladay. On most records her last name is spelled Holladay. On other it is spelled Holliday. I am not sure of correct spelling.

My uncle told me that Mable and Clarence where separated towards the end of their lives. I don't know Mable's Maiden name. My uncle told me Mable died May 18, 1980, where she lived is unknown but at some points she must have resided in Oklahoma, California, and Washington. Clarence must have lived in Oklahoma and California as well. Due to now know Mable's maiden name I am unable to get my Grandma's birth cert.