Frona R. Medlock b. 16 Feb 1890 and died 15 Jan 1970 is on a headstone with Daniel A. Medlock b. 24 Jul 1880 and died 16 Feb 1964. The stone is located in the Dexter Cemetery in Stoddard County, Missouri. They were listed on the 1930 census of Dexter, Stoddard, Missouri. Daniel was listed on the census as Bea Medlock, male, age 50, born Arkansas. His wife is listed as Frona Medlock, female, age 40, born Arkansas. A stepson, Robert Ellis, age 17, born Missouri, is living with them. This appears to be your grandfather. Also, they have a son, Bill Medlock, age 12, born Missouri, living with them. According to the sons' birthdates, they were probably married between 1913 and 1918. I have seen no record of marriage or location in any other census record other than 1930. They seem to have lived in Stoddard County for many years. Local newspaper obituaries might assist in obtaining further information.