First two given names, date of death, estimated year of birth, Australian State of burial, from a photo of headstone in a Facebook Post by granddaughter Rhonda Boyland (nee Anlezark) on 10 October 2023:
Arthur S A Radnidge
Died 26th August 1968 Aged 66 years
Also
Ruby Myrtle Radnidge
Died 30th May 1990 Aged 82 years
Our dear Nan & Pop
In God's Garden

Place of birth, name of parents, from the Australia Birth records, found in November 2023:
Name: Ruby M Keasey
Birth Year: 1908
Birth Place: New South Wales
Registration Year: 1908
Registration Place: Maitland West, New South Wales, Australia
Father: Frederick J Keasey
Mother: Miriam N Keasey

Maiden name, year of marriage, place of burial at Cessnock Cemetery, photo of headstone, from Find a Grave website found in November 2023:
https://www.findagrave.com/memorial/144853612/ruby-myrtle-radnidge
Name: Ruby Myrtle Radnidge (nee Keasey)
Birth Date: 1908
Death Date: 30 May 1990 (aged 81–82)
Death Place: New South Wales, Australia
Burial or Cremation Place: Cessnock, New South Wales, Australia

Place of marriage from the Australia Marriage records found in November 2023:
Groom: Arthur S A Radnidge
Bride: Ruby M Keasey
Marriage Year: 1925
Marriage Place: Cessnock, New South Wales
Registration Year: 1925
Registration Place: Cessnock, New South Wales, Australia