Could be Native American.
There WERE tribes in the Bahamas before the British built plantations manned by slaves. Not all of the Natives got killed off. But this seems unlikely though.
Actually... what DO we know about Monet's ethnic heritage?
1: her paternal grandfather is a "white" rich guy from Monaco.(25% white)
2: she was born in Algeria to a woman who was seemingly an Algerian Berber.(50% Berber)
3: we don't see her paternal grandmother but her father has darker skin than his father did, so her paternal grandmother wasn't "white". (25% unknown)
So, by that logic 25% "black" at most.