Are you seeing mole hills - mounds where they have pushed the soil they are moving making the tunnels up above lawn? Often that's the first sign of moles to the gardener, the mound...

If it is moles, killing grubs in an otherwise healthy lawn isn't going to get rid of them, you'd have to counter productively kill all your earthworms too because worms are a favorite food of moles. I know this without a doubt but I'll save my story of why I know unless you need convincing :)

There are a couple of repellents on the market that are only partially and temporarily effective, the final word on moles always seems to come back to trapping with other methods being anecdotal, ineffective.

I'd give them my lawn, but moles never bother with it, preferring my perennial and shrub beds where the mounds (smothering perennial crowns) and tunneling can cause more $$$ damage :(

Here is a link that might be useful:

I do see the mounds

Other than trapping, about the only thing I've seen on the market that might possibly show some promise is Talpirid baits that is said to look, feel, and smell (to a mole) like a real earthworm but I don't know if they would work for you and am not endorsing them. They are somewhat new, within the last couple of years, and expensive...

Here is a link that might be useful: WSU.edu mole

It's worth keeping in mind that moles will enter a territory in order to explore...whether there is a food source or not.

Well they must have found food because they have stayed for quite some time now. As for the Talpirid bait, I don't really want to spend a lot of money that isn't guaranteed.

Because most people know that earthworms are good to have in the soil no one selling products meant to control moles will tell you that those products will kill the earthworms. They will tell you the products will kill the grubs, those nasty larva of beetles, that everyone has been taught to hate. Since the people that study mole behavior will tell you that what they find in the stomachs of moles in mostly earthworms that means the moles like earthworms better, or the moles find earthworms easier, or there are not as many grubs for the moles to eat as everyone thinks.
Most often, a mole needs about 1/4 acre of territory and will fight to keep other moles out of there, so most of use just have one mole, not moles, to deal with. That one mole can be very active and those tunnels you see are feeding tunnels. Numerous things have been proposed about controlling moles and most do not work. Traps are probably the most effective, but I know people that have caught 40 to 50 moles in those traps every year for the last 40 years and have not decreased the mole population even a little.
Spraying 1 pint of Castor Oil over 2,500 square feet has been found to be effective in repelling moles for about 6 weeks when that needs to be repeated. Less then that is not effective, more is a waste of money, but even that is quite expensive.