Questions about your typical yard snakes...?

my aunt is TERRIFIED of snakes, when they pulled into the driveway this evening there was a good sized king snake laying there. my uncle caught it and transported it to the country. they were wondering what they could put down in their yard to prevent snakes from coming into the yard/house. they have their 14 month old granddaughter living with them, so it needs to be something kid safe. also, can snakes come in through the fireplace? thanks in advance. no rude comments please.