Please don't kill them.. I love reptiles and they are one of mans best friends so just don't resort to killing them.
A few suggestions - move hiding spots away from the home. Large piles of sticks, debris, lumber, etc.. Snakes will use it to hide in during the day and in an area with venomous snakes you should exercise caution when moving these items as they may be present in the debris piles.
Do your best to decrease rodent populations. Snakes are actually pretty lazy creatures and will not want to stay long in an area where finding food requires a lot of effort. Also, if there is a koi pond on the property you might want to consider getting rid of it as many species will use it for soaking, drinking water or will eat the fish which flies in the face of not providing a good hunting ground for them.
Outside of that they are pretty much gonna do what snakes do and there is not much of a way to prevent it. I will note that it is a GOOD thing to have kingsnakes on the property. There are native populations of rattlesnakes in Florida and kingsnakes are immune to rattlesnake venom and are their chief predator with many kingsnakes often making an entire diet out of rattlesnakes.
Rattlesnakes are good as well but at least it greatly reduces the risk of having a rattlesnake problem on your mom's property.
They manage the mice coming in from the nature trails and from under the neighbor's deck.
