* Mythology vs. Reality: Greek mythology is a collection of stories and beliefs, not historical fact. There is no evidence that gods and goddesses actually existed, and therefore no way to know what language they would have spoken.
* Ancient Greek: The language of the Ancient Greeks, which we call Ancient Greek, evolved over time and had regional variations. It's likely that the language of the gods in mythology reflects a kind of idealized, poetic version of ancient Greek.
* No Direct Evidence: We have no written records of gods and goddesses speaking directly.
In Conclusion: While we can speculate, there's no way to know for certain what language Nike the goddess spoke.