Answer:
Fe^2+(aq) + S^2-(aq) --------> FeS(s)
Explanation:
First let us look at the molecular equation;
Na2S(aq) + Fe(NO3)2(aq) --------> FeS (s) + 2NaNO3(aq)
Now, the net ionic equation usually shows the most important reaction that took place, in this case, the formation of the FeS precipitate.
Hence, ionically;
Fe^2+(aq) + S^2-(aq) --------> FeS(s)