4th BSOD Bad Pool Header in the last hour

All dumps point to Malwarebytes Anti-MAlware as the cause. Uninstall it and see if the problem goes away. If yes you can try reinstalling the latest version but if the problem comes back then you will have to uninstall it again. I suggest also posting in the MBAM forum: Malwarebytes Anti-Malware Help - Malwarebytes Forums

Code:

BugCheck 19, {20, ffffe000c01b7d20, ffffe000c01b7d40, 4020010}

*** WARNING: Unable to verify timestamp for mwac.sys
*** ERROR: Module load completed but symbols could not be loaded for mwac.sys

Code:

Mwac.sys file information 	The process known as Malwarebytes Web Access Control 
belongs to software MBAMWebAccessControl or Malwarebytes Anti-Malware version 
by Malwarebytes (Malwarebytes | Free Anti-Malware & Internet Security Software).

Code:

BUGCHECK_STR:  0x19_20

POOL_ADDRESS: unable to get nt!MmSpecialPoolStart
unable to get nt!MmSpecialPoolEnd
unable to get nt!MmPagedPoolEnd
unable to get nt!MmNonPagedPoolStart
unable to get nt!MmSizeOfNonPagedPoolInBytes
 ffffe000c01b7d20 

CUSTOMER_CRASH_COUNT:  1

DEFAULT_BUCKET_ID:  WIN8_DRIVER_FAULT

PROCESS_NAME:  mbamservice.ex

Doing a bit more research it seems Bitdefender can cause MBAM to have problems.

If uninstalling MBAM resolves the problem and reinstalling it brings it back, you may want to look at uninstalling Bitdefender and running with the built-in Windows Defender for awhile to see if that really fixes the problem.

This is a known issue with Bitdefender and Malwarebytes.