I had the same problem until yesterday, but was able to pinpoint it to AVAST Pro only. It does not happen with AVast Free.
Situation: Windows 8.1 Pro, one kids account with Family Safety on (incl. Web filtering), another (admin) account without Family Safety. After Installation of AVAST Pro 30-Day-Trial (on oct 6th) I had spurious BSOD Unexpected_Kernel_Trap as described above (up to 4 a day) ONLY if using the kids account.
On a 2nd laptop with identical hardware and software, but using AVAST FREE, there were no problems at all.
Using Microsoft "Driver Verifier" with the settings as described in
http://www.techsupportforum.com/forums/f299/bsod-0x7f-ntoskrnl-exe-153fa0-whie-playing-game-870850.html , I was able to provoke the BSoD every time I logged in to the kids account. It never happed with the admin account.
So I downlevelled the Trial-Version of AVAST Pro back to AVAST Free (using the builtin downlevel feature), and the BSODs were gone. So that is the solution for me - sticking to Avast Free.
@AVAST: This should give sufficient information to track down this bug in co-existence of MS Family safety and Avast Pro in the current version (oct 6th - Oct 19th)