One ring to find them all

[Gabbysdad]

Looks like the ring is somewhere in Ostoya I go to where the exclamation mark is and there is no one in that area.

[Oga]

The quest explains why it points you there.

If you wanna finish, spoilers below:
You can either walk toward the nearby camp and buy one for 1500 gold from a shady figure
or you can grab it from the house in the far corner of the water, it's on a barrel on the right side of the front door...
Also, it's not her ring, she has it in her pocket

*cough*inspectormode*cough*

[Malic]

Its a great quest and a homage (I am assuming given the narrative) to Tolkien. Oga's answer above should resolve any issues youre having.