What version of McAfee are you using? Is the taskbar icon a square with an M inside or a white-rimmed shield with an M inside or a red/blue shield?
Once a file is quarantined it is harmless because McAfee encrypts it. If you've found the Quarantine folder you can remove it and it will de deleted from your system. Don't restore it if you don't know what it is and are sure that was the cause of your problem.
The one that looks like a square with a M inside it, apparently this is an old one.
So now it's quarantined I don't need to worry?
No need to worry but if you want to delete it you can and then it's gone.
I'm going from memory here so forgive me if the instructions are not quite right.
Double-click the taskbar icon to open SecurityCenter
Click Advanced Menu (bottom left)
Click Restore (left)
Click Files (right)
It should be listed there and if you highlioght it you should have options at the bottom.
Remove will delete it altogether.