I think its okay to assume in this case that the ionic compound would be less volatile than the covalent one. Thought we cant make such a statement about all ionic and covalent compounds.
For option 4, the ionic one would just dissociate or dissolve in water.
The covalent one can undergo hydrolysis like the OH- of water attacking the M in the covalent one probably by SN2.
Ill state a line given in JD Lee with regard to the same:
For SnCl4 and SnCl2 the hydrolysis rate is SnCl4 > SnCl2 due to higher charges on the former.