User blog comment:FallenShadow/Fallen's Reviews: Chapter 341-343/@comment-3177613-20130711194157/@comment-4829046-20130712024324

I think its safe to assume Mavis dies(or simply shifted to the island) within the next 10-15 years of founding FT or else Makarov would have remembered her. Now we only need to know exactly what time Zeref appeared on Tenrou and Mavis started to stalk observe him.