Statement-I: Oxygen can have oxidation state from −2 to +2, so statement I is incorrect
Statement- II: On moving down the group stability of +4 oxidation state increases whereas stability of +6 oxidation state decreases down the group, according to inert pair effect.
The inert-pair effect is the tendency of the two electrons in the outermost atomic s-orbital to remain unshared in compounds of post-transition metals.
So both statements are wrong.