So much instability recently but don't know where to start looking!! Help

In a nutshell, if the application tells you your system should be capable of real time audio, at this point you should be fine. Later it is a useful tool for optimization. However, iF you are having a large number of hard page faults, you can track those down on the "Processes" tab. If there are any other problem areas, you can, for example, go to the driver tab and click on the top of the "highest execution (ms)" column - to see which driver file is consuming the greatest cycle time.
Can you load SONAR with a small basic project without a crash? Say a simple soft synth, single track? If so, I would run LatencyMon as a baseline without SONAR, and as well as with SONAR running with the project loaded.
What driver version are you using on your audient? If it's current, I would try rolling back one version, etc. If you still have access to the laptop, can you try the audient with it? IF you still have access to the laptop, have you tried it with the audient?
Usually motherboard audio devices are not a problem. I use my motherboard's audio for system sounds myself. It's the HDMI device which can create a conflict. 
 

OK almost all your recent crashes are Sampletank 3.  Some are the VST2 version, some the VST3 version.  (a few of the crashes are just SONAR itself, one crash from Melodyne, and one Kontakt crash).  But of the July 2017 crashes it's really just Sampletank 3.  In some of the older crashes your using a ZOOM ASIO driver but all the recent ones are the Audient.  There isn't really anything that sticks out though.  So if I were trying to fix this I'd do simple things:
 
I'd uninstall Sampletank 3.  Then completely delete it from c:\Program Files\IK Multimedia\SampleTank 3 and C:\program files\Cakewalk\vstplugins and c:\Program Files\Common Files\VST3.  Don't delete/uninstall your sound library, just the software itself. 
 
Then I'd start SONAR, not open a project, open the plugin manager (from inside SONAR) and then I'd go into the VST options, make sure the paths are correct (and include the VST3 paths) and do a full reset and then rescan everything (without Sampletank installed).  Then when it was done, I'd exit the plugin manager, then exit SONAR and reboot.
 
I'd make sure if I'm running Windows 10 I've turned off Game Mode (see this blog post http://blog.cakewalk.com/windows-10-creators-update-your-daw-is-not-a-game/ )
 
I'd download and install the latest 2015 C+ Runtime and the 2017 C++ Runtime from Microsoft
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads
and (direct link to the 2015 runtime)
https://www.microsoft.com/en-us/download/details.aspx?id=52685
(the version of VCRUNTIME140.dll you are running is earlier than the one I have)
 
I'd make sure I apply all Windows Updates.
 
I'd get the newest Sampletank 3 from IK (they just shipped an update last week).  And I'd install that.  Then start it stand alone and make sure everything works right there (configure its ASIO standalone settings).  Then start SONAR and let it find it.  It should find both the VST2 and VST3 versions. 
 
While I believe the VST3 version is buggy with SONAR, if you have a project that uses the VST3 version there is no way to "convert it" short of opening it, saving the multi, then removing it and adding the VST2 version and reloading the settings.  That's super painful and I don't recommend it.
 
Sampletank 3 does have issues when the latency on the audio device is too low,  I know it has pushed me to increase my ASIO buffer more than once to get it to stop crashing (I've got a Sampletank 3 test project that won't play without stuttering/stopping unless I have my ASIO buffer set to 20msec, lower than that and it will hiccup, much lower and it crashes.  But my older Focusrite Saffire isn't exactly a low latency device).  I'd consider doubling whatever you are using now, if you can try something 4 times what you have been using.  Even if it's not usable at that level, it might help you narrow the problem.
 
You might also want to try changing SONARs options for Plug-In Load Balancing.  I'm running with it and the multiprocessing engine on, but there are forum posts of problems that the load balancing seems to be causing.
 
I doubt though any of this will fix your problem, though it might push it out or delay it.  If it still happens, then start trying to produce a reproduction case.  While the problem really is Sampletank 3's code, I don't think IK support will be of much use.  If you can get it to happen on command you might at least get them to look at it.  You might want to contact them and see if they can offer any advice, just because I've not had any luck with them doesn't mean you won't.  Good luck.