Though floppity did a great job overall with the transcript, I do believe the "tombstones" part is a mistake and was misheard. I believe the correct dialogue is:
Chad: "So we'll see what transpires."
This makes more sense given their previous discussion of law enforcement searching the property as they can only wait and see what happens as a result of the search. Furthermore, I don't believe they had any kind of "tombstone" or other marker identifying the gravesites, excepting the puppy statue marking the pet cemetery in general. And to mention "tombstones" in a phone call they knew was being recorded surely would have been the last nail in their coffins so to speak (forgive the pun). But you can listen to the audio and decide for yourself what is said. You'll find it at the 1:38 timestamp: