“Fail To Remain Summons”

My father (74 yrs old, non English speaking) got charged yesterday with Failure to Remain. He was going to church at 7:45am, struck a pedestrian which he didn't realize he hit and went to church (which was approx 15 feet away from the accident site. He parked his car, someone said something to him in English which he didn't understand and went to church. When he got out of church, the police were there and charged him with failure to remain, the cop mentioned he had a clean driving record. My dad honestly did not see he hit someone, his actions did not resemble someone who purposely was trying to speed off, flee and hide because the church was just across the street. He is devastated at the fact that he hurt someone.

I am going to hire someone - best case scenario is he gets off, what is worst case scenario?

How does his age impact this?

Thx