Can someone help me evaluate if this is a scam for Mac support?
Your gut reaction feels correct. The description of sleeping processes and idle % CPU use is misleading.

The description of tracking IP addresses to a single location is unrealistic.

The costs involved are high. For that sum, consider suggesting your father-in-law engages a local Mac expert – or go to a local Apple Store for help.

Erase and Reinstall

If possible, back up your father-in-law's Mac to an external hard drive. Then erase and reinstall OS X:


  
  Before you begin, make sure your Mac is connected to the Internet.
  Restart your Mac. Immediately hold down the Command (⌘) and R keys after you hear the startup sound to start up in OS X Recovery.
  When the Recovery window appears, select Disk Utility then click Continue.
  Select the indented volume name of your startup disk from the left side of the Disk Utility window, then click the Erase tab.
  If you want to securely erase the drive, click Security Options. Select an erase method, then click OK.
  From the Format pop-up menu, select Mac OS Extended (Journaled). Type a name for your disk, then click Erase.
  After the drive is erased, close the Disk Utility window.
  If you’re not connected to the Internet, choose a network from the Wi-Fi menu.
  Select the option to Reinstall OS X.
  Click Continue and follow the onscreen instructions to reinstall OS X. 
  


This should entirely remove any third party tools and processes that have been installed by the support company.

With the reinstalled OS X, only restore personal files and documents from the back up.

An Aside: Distractions and Blame

Please do not blame the father-in-law. We have not been asked to judge the company or individuals affected. @milesmeow asked for help to decide if their decision was defensible and if others have encountered this type of situation.