IMHO the hosts file looks good, it's blocking bad entries... but run the tool Dieselman recommended anyway.
Then try this: Go to Avast, Settings (upper right corner), Update --> set to "no proxy" and "always connected to the internet", try again updating.
If it won't help, the start the Avast installer again from the control panel / add/remove programs and scroll down on the left side and choose "Repair".
Reboot and retry updating.