Grounding a 3-wire sub-panel in attic
Option 2 is the only one that will improve safety here.  

A single wire break should not create a dangerous condition.  But that is exactly the situation you have, because every circuit in the subpanel has a bootlegged ground.  If that neutral wire fails to make good connection, the ordinary loads in the subpanel will "pull the neutral hot". That normally wouldn't be a big deal. But because all those grounds are bootlegged, it will ”pull all the grounds hot” too.  So now switchplate cover screws or the panel cover itself can bite you.  

By trying to put on grounding theater, the last guy made things worse than no grounds at all.  Worse, Code once endorsed this, and still does where dryer and range sockets are concerned.  

Now you don't have to go back to the panel.  It will suffice to reach the grounding electrode system, i.e. The bare wire running to those two ground rods.