According to various sources that I found while browsing the web, task.vbs can indeed be a dangerous file used by several different malware. Furthermore, as far as I know, the file hasn't been a part of the operating system since Windows Server 2003, so I don't think there's any danger in allowing Norton Security to remove it.
However, just to be sure, you could have the antivirus quarantine the file and see what happens or create a Windows backup so that you have something to go back to if needed.