Just passing along my recent experience with Avast Free and BSOD's.
I've had Avast installed for several years, without it causing any apparent issues. But I'd been having BSOD's on my Windows 10 desktop system over the past couple of months, more and more frequently to the point of having up to four per day. Most of them were shown as being memory management related, and there were other causes as well. I'd tried everything I could find from researching this; drivers, virtual memory, running MemTest over and over...all the standard troubleshooting approaches.
Then I happened to come across reports of people having BSOD's and finding out that Avast was the culprit. After reading these reports, at first I turned off all the Avast shields but the problem was still there. So I completely uninstalled Avast a week ago and haven't had a BSOD since. I've also seen big performance improvements on loading of large files in different programs.