The fifth nerve innervates the following:
Mylohyoid, anterior and posterior belly of digastric
Mylohyoid, anterior belly of digastric, and tensor tympani
Mylohyoid, posterior belly of digastric and tensor tympani
Mylohyoid, posterior belly of digastric, Stapedius and tensor tympani
Trigeminal nerve is the 5th cranial nerve. It is a mixed nerve containing both the motor and sensory fibres but predominantly it is sensory.
It is a motor nerve to the muscles of mastication and several small muscles and the principal sensory nerve of the head and face.
It consists of three large nerves: ophthalmic, maxillary, and mandibular, hence the name trigeminal nerve (L. trigeminus = triplet).

Key concept:
Mandibular nerve supplies muscles of mastication mylohyoid, anterior belly of digastric, and tensor tympani.
Posterior belly of digastric and stapedius are supplied by Facial nerve.