But Eostre was the name of a goddess, even at that--the word
as a word may not have a religious meaning, but it certainly did at one point. Which makes it doubly weird to use as a personal name honoring a different religion--and, as has been noted, mileage may vary on any explicitly religious name.
Word-names tend to veer toward the cheesy anyway, in my opinion, and your friend would probably do better with
Agnes,
Lily,
Rachel, or
Pascale. Even
April would be a marginally better name, and that's the month in which
Easter falls next year.