Avast does not control the file hosts C:\WINDOWS\system32\drivers\etc\hosts. Offered! Avast should control the hosts file. It is also required to recover, if the file hosts has been modified virus!!!
Welcome to the Forum AlexM,
There are many programs that watch and notify you if there is a change
made to you host file.
WinPatrol among other things also watches and notifies you of such activity.
Looked down at my tray. Scotty is on Patrol.
Doesn’t Windows Defender do this as well? I remember getting a popup ages ago…
That being said, I think Winpatrol is the way to go, I only recently tried it and now have it installed on my computer 
(Funny, Scotty is a name I respond to…naturally ;D)