The graffiti in question are from the fourth century AD. Here is the abstract (read more here) of the scholarly paper:
Recovering Christian Abydos: Coptic Graffiti from the Temple of Seti I
Jennifer Westerfeld (University of Louisville)
Abstract:
The temple of Seti I at Abydos was the site of intense epigraphic activity from the Late Period into early Islamic times. A significant corpus of late antique graffiti from the temple appears to have been produced by a community of Coptic nuns who periodically visited the site. Although such a collection of epigraphic evidence for female monastic activity is virtually unparalleled in Egypt, this material has never been fully edited or studied. This paper will discuss a newly-proposed research mission to document the Coptic graffiti at the temple of Seti I, considering in particular the circumstances under which the graffiti were produced and the ways in which the Seti temple functioned within the Christianized landscape of late antique Abydos.