I would say that this may be an old restore point now detected or something previously found as infected and dealt with being saved into system volume information folder by system restore and now detected by avast.
Remember the reason why thins are in the volume information folder is because they were deleted or moved from the system folders, etc. and a copy of it saved by system restore. If there is any element of doubt in a restore point it should be out of the volume information folder, so at some point in the future if you use system restore you could infect your system.
Personally if you have no other symptoms and have sent to file to the chest there is little to worry about. However we tend to suggest other tools to confirm that all is clean, personally I wouldn’t go overboard and just use two tools MBAM and SuperAntiSpyware.
I wouldn’t disable system restore unless I had a problem in removing an infected restore point as that removes ALL restore points, not just the infected one.