The correct answers are Many of the artifacts were recovered from the getaway vehicle, Most of the security cameras had been disabled, and None of them saw the culprit enter the vault.

When we use a quantifier (like many, most, some, none) followed by "of", the noun that comes after it MUST be preceded by a determiner (like the, my, those) or be an object pronoun (like them, us, it).

Therefore, "Many of artifacts" and "Most of security cameras" are incorrect because they lack a determiner (like "the") before the noun.