Sodium hydroxide (NaOH) and elemental sodium (Na)

acetic acid (CH3CO2H) and hydrochloric acid (HCl)

acetic acid (CH3CO2H) and ammonia (NH3)

ammonia (NH3) and ammonium chloride (NH4Cl)

If the question is which can make a buffer, then NH3, NH4Cl should be correct. Because Ammonium (NH4) is conjugate acid of NH3 so they can form an equilibrium which is basically a buffer whose purpose is to resist pH change.