Your minidump files mostly indicate the virtual driver on the Vanguard anti-cheat is causing your PC to crash, two of the minidump files also indicate the network drivers contributed to the crashes.
Go to the support page for your PC on the manufacturers website, then from there, download and reinstall (not update) the version of network drivers they provide.
If that does not resolve the problem, then if you have updates your BIOS and reinstalled Vanguard, the best option may be to contact Riot Games support to ask them if they have an update for the Vanguard anti-cheat.