You can pretty easily derive the meaning of AE when it appears like this on a tombstone: clearly, it signifies “aged,” as in aged a certain number of years at death. In Latin, “anno aetatis suae” means “in the specified year of a person’s age.” AE, which should actually be squished together so that the rightward most stroke of the A is also the vertical line of the E, is an abbreviation for that.
A Grave Concern 