The hit-and-run driver turned himself in the next day, accompanied by his father.
Literal
Hit-and-run [gen-の] perpetrator [topic-は] next-day father [by-に] be-accompanied-[and-て] turned-himself-in [came-polite-してきました].
伴われる is the passive of 伴う 'to accompany,' giving 'be accompanied by X' — with the agent of the accompaniment marked by に. 自首してきました combines 自首する 'to turn oneself in (to police)' with ~てくる, here in the sense of 'doing X as a development / showing up to do X,' yielding '(they) showed up and turned themselves in.' ひき逃げ (轢き逃げ) 'hit-and-run' literally 'to hit and flee.'