Judging from the text listed on the Wikipedia article on the place of Morea (take them for what they're worth), I am
very inclined to say moh-REH-ah (it is not REE). The only other site I have found so far with the Greek script in reference to the nymph is this one, but it is without the stress marks:
http://www.theoi.com/Nymphe/NymphaiHamadryades.html
~~~~~Amanda~~~~~You left me lonely and confused
Question, questioning you
So soon goodbye you stole my heart
I'm believing you
Was it a lie right from the start
Answer, answer me do"
-The Corrs