Trapping and management vary significantly among several species (e.g., gophers, voles, ground squirrels, and others) that are often called "moles." Mole hills would be closed, relatively round, and have a slightly depressed or sunken plug right in the middle. If the sign you are seeing there are different, then we need to diagnose what species is actually present. 
If these are moles, which eat subsurface invertebrates such as worms and insect larvae, then the solution is to manage your yard to not have those animals (the insects and earthworms) in abundance, either through changing your watering routine or changing the vegetation so that there is no habitat for the invertebrates - and thus no habitat for the invertebrate-eating moles. Individual moles can be lethally trapped with body-gripping traps specifically made for moles, and you have to use the freshest hills to identify in what part of a run or tunnel the animal is currently working and feeding.