It might depend on who the informant was for the following death record as to whether they had the correct information for Clarence's mother's maiden name.I suggest you obtain a copy of the application for his Soc Sec card.Clarence filled that out and it should show the names of his parents, including his mother's maiden name, his residence at the time of the application and other data, too.
CA Dth Idx:
Joyner, Clarence, b 9 Aug 1901 TX; d 22 Aug 1957 San Francisco Co, CA; 57 yrs old; mother's maiden nane Raines.
Keep in mind some Southerners would pronounce the long "a" in Rain almost like an "i" in Ike.My husband's cousin from TX came for a visit and when she introduced her little girl we thought her name was Dinah, finally she had to spell the name and it as Dana.
I see you have death date for Hubert, so if you're still not sure, you might check records for Hubert, see what maiden name is given for his mother.