Oxidizing and reducing agent
I agree with Ivan Neretin in that the sodium oxidation state is equal in all compounds, and it will not act as oxidizing or reducing agent. 

My thoughts:

Na$_2$O will not act as a strong oxidizing or reducing agent, as both ions are in their preferred state. 

NaO$_3$, or sodium ozonide, will likely act as an oxidative agent. However, I believe it disproportionates in water: 4 O$_3$ $^-$ + 2 H$_2$O $\rightarrow$ 5 O$_2$ + 4 OH$^-$, so that's kind of a candidate: it goes from oxidation state -1/3 to 0 and -II. 

NaNO also seems strange to me - if it's Na$_2$N$_2$O$_2$, I see here that it acts as a reducing agent. 

NaNO$_2$ can certainly act as both reducing and oxidizing agent, as the nitrogen atom is in oxidation state +III. 

In conclusion, (4) seems to be the safest bet, considering only one answer is expected.