In the story of an hour is the narrator limited or omniscient

The narrator is limited.

Omniscient would mean that she would know everything. The fact that the main character does not know that her husband is alive is precisely what drives the narrative. Indeed, "The Story of an Hour" is about the successive thoughts and feelings (grief, and then joy from a sense of freedom) crossing the mind of a lady within the hour after the was told her husband had died, before she learns he is actually alive.