TVS.inf, TVS.sys and TVS.cat are the driver install files. VERVARS.reg is a registry file for the new signed driver. This file adds two entries to the Windows registry when the new USB driver is installed. The two entries are; 

HKEY_LOCAL_MACHINE\SYSTEM\TUSB\VERVARS\WatchDogOn
Allowed values: 0 or 1
This entry is needed to support ESD recovery. If ESD recovery is not required the value 0 can be specified for this variable. 
Default value is 1.

HKEY_LOCAL_MACHINE\SYSTEM\TUSB\VERVARS\SetWriteCount
Allowed value: 1This entry is needed to return the correct number of bytes sent to the printer, when a write call is made using the USB driver. This value should always be 1, else usb write operation might return inconsistent results.

It is necessary to run the VERVARS.reg file prior to the signed USB driver installation. 
If the VERVARS.reg file is executed after the driver is installed, a system reboot is necessary so that the driver gets reloaded and can read the latest registry variables.