Hi Georgeanna.
I do a lot of research for families in Granville County,NC, but I don't think there is a book which specifically deals with just FPOC in that county. There are, however, books which contain Wills and Deeds information for the people of Granville,among which were many FPOC. I haven't seen much on the HAWLEY name in those records, with the exception of a minor one, which also is included in Paul Heinegg's work.

From "History and Genealogies of Old Granville County,North Carolina 1746-1800", by Thomas McAdory Owens:
Pg.227, Slaves and Slavery-
(Nov. 3, 1784) LABAN HAWLEY, aged 2 yrs, "a Freemalater" a base born child of JESSE HAWLEY, bound to DAVID BRADFORD until 21 yrs; to become planter.

As for the name of WILLIAMS, I haven't come across any specific records that indicated anyone as FPOC with that surname in Granville County,NC. I am researching several different lines of WILLIAMS in North Carolina,one being my Gr-Grandfather who was a slave in Warren Co.; another being from the white WILLIAMS family that settled in Warren & Halifax Counties; and another being the white WILLIAMS family that lived in Granville County, and later moved to Kentucky and beyond. There are many, many references to these families who were quite wealthy and well known in the early days of North Carolina, and most of them were large landowners and easily identifiable to those doing research on them. If you have the names of the people you want to research, it would be a good idea to look for records containing those names and then deciding if it is one you are looking for.

Deloris