How is the panic card affected by Range?
Yes, you can use a panico card to take a card from someone who is two places away from you if you have a scope. 
 As per page 7 of the bang rules:


  Panic!
  
  The symbols state: “Draw 
  a card” from “a player at 
  distance 1”. Remember that this distance is not modified by 
  weapons, but only by cards such as Mustang and/or Scope.


Remember there is a difference between "number of places a player is away from you" and "range". Consequently, I would probably word your example a little differently:


Panico only works on players who are at range 1 from you.
If you have a scope (and no one else has any range affecting cards), the two players to your left (and the two players to your right) are both at range 1 (range can never go below 1), so you can panico from any of those four players. 


I think wording it this way is less confusing - you can never panico cards from someone who is at range two - but, you can reduce the range of a player who is two places away to range 1, by using a scope.

Similarly, if your neighbour has a mustang, yes, they will be at range two, and no, you cannot use a panico card to take a card from them.



As an aside, remember that range adjusting cards stack - say you have a scope, and your immediate neighbour (Jane) to the left has both a mustang and a hideout, while the player to her left (Bob) has no blue cards. 


Jane's range from you is 2:  1 for the number of places, +1 for the hideout, +1 for the mustang, -1 for your scope. You cannot panico from her, even though she is one place away.
Bob's range from you is 1: 2 for the number of places, -1 for your scope. You can panico a card from him, even though he is two places away, past Jane.


Just remember each card in play in front of you needs to be unique (amongst your tabled cards). But, you can have cards with a duplicate effect in play, as long as they have different names.