Grady Cemetery _is_ located in Fisher Co, TX and is also known as the McCombs Cemetery. Surnames for those buried there (as of 1989) with existing tombstones: Phillips, McCombs, Brantley, Rivers, Blount, Robinson, Minor, Royalty, Reep, Berry, Skaggs, Hill and Donald.
If your ggGrandmother is buried there, she may not have an existing tombstone if she was buried before 1989. She isn't listed in the Fisher County Cemetery book.
You might contact Weathersbee Funeral Home in Rotan, TX to see if they handled the burial if you have a date.
Keep in mind, too, that more than 75% of the city of Hamlin is in Jones Co, TX - very little of it is in Fisher County.