Simple Voltage Range Circuit
You can make something like the following, however its not within the two component limit. 

It's a window comparator. It produces 11V-12V when the input voltage is within range of the upper and lower vrefs and produces a zero when its out of range. You can then use this output to drive some sort of switch to allow your signal to go through or not. Clearly this is not a 2 component solution. You can however make this count even smaller by buying a window comparator rather than making one. 

If you have a relay that can be driven from an comparator/opamp directly then great. Otherwise, you will need a switching transistor in between the relay and the output of the comparator. 

Whicever way you go, it doesnt look like you can do this with one or two components. 







simulate this circuit &ndash; Schematic created using CircuitLab

Edit

As @EmFields pointed out (Thanks!), the way the schematic was set up would actually not work because the opamps would always be on. Now the output goes low when Vinput is within range, and goes high when its out of range. 

Edit 2
See comments.