Couple of things you can try - CA an allen wrench into the stripped socket head - sometimes will give you enough grip taht you can get it out. Just enough CA to wet surface - too much and it won't dry/cure. had mixed results trying this.
Next one - take next biggest allen wrench and file on the sides or flats of the wench a little at a time until you can drive it into the stripped head. That usually works for me, it just takes a little time.
Can minimize these kinds of probs if you use quality, hardened allen drivers and hardened alloy steel hex heads.