Considering they aren’t actually reporting rootkits, just hidden files. and a .log file at that, not essentially what a rootkit is going to be.

TDSSKiller is an even more specialist rootkit scanner, looking for a particular rootkit variant and it is correct in that it didn’t find a TDSS rootkit.

At least Sophos advises against cleanup as it hasn’t any information, whilst it says it is removable, I would rather hope that the avast self-defence module would have something to say about that.

Avast already has a rootkit scanner incorporated into the program (runs 8 minutes after boot) and it is based on the GMER rootkit scanner. But it goes further than GMER in that it isn’t just an analysis tool, it seeks to take the decisions away from the user where possible. It is also incorporated into the various on-demand scans (at different levels of thoroughness).

So I don’t understand why you were running these anti-rootkit scans ?
Generally these are specialist tools that are run if you have a suspicion that something isn’t right on your system.

Using old applications or ones that haven’t had any development in some time are not going to have kept up with developments isn’t advised, as the security applications on systems have continued developing.