Using Google Books, I have found several examples of epitaphology. The oldest example:

But I wish to refer particularly to one feature of Epitaphology—pray let the term pass, notwithstanding its rudeness—which is of the greatest historical, moral, and philosophical importance. Only let us collate a few monumental inscriptions, and we shall arrive at a surprising fact of which few traces are to be found elsewhere. I allude to the extraordinary virtue—indeed, I might almost say, to the impeccability—of the human race; or, at least, of those individuals who have been rich enough to purchase tombs, or fortunate enough to possess friends willing to compose their Epitaphs.

--from an article "Epitaphs" by Basil Lincoln, in The City of London Magazine, Vol. 1, No. 3, December, 1842.