Answer
Ammonium sulfite.
Work Step by Step
Ammonium ion $NH_{4}^{+}$ has a +1 charge whereas Sulfite ion $SO_{3}^{-2}$ has a -2 charge. In order to balance charges, two atoms of ammonium ions should be present. Therefore the chemical formula will be $(NH_{4})_{2} SO_{3}$ and the name of the ionic compound will be Ammonium sulfite.