Have you tried searching for her on the social security database?You might try Pentecost, Penticost, Pentycoas and Pentecoast as variations, if you think you may have mispelled the name.
There were Pentecosts in Alabama who descended from William P. of Georgia.The Capt. John Rees married Mary Pentecost in Bristol Parish Va., and moved to Santee River, S. C... Mary believed to be dau. of George, and William P. of Georgia would have been George's grandson.I have heard also that another of George's children Anne married and lived in S. C.
I don't find any Pentecost surnames living in S. C. though, but I do know there was some connection to Pentecosts and other surnames visit Anne (married name unknown) and Mary Rees?We all want to more about the South Carolina connections.Good luck.