Stripped allens
I'd soak 'em with Kroil and leave 'em overnight, then insert the appropriate size screw remover and twist 'em out.
Screw removers come in sets; I bought mine @ Sears years & years ago; other good-sized hardware stores should have 'em also.
In a less "tricky" place, I'd mebbe drill out the allens some more before trying the screw remover, but given the screws in question are on a 'scope mount--and 'scope, and rifle--that you don't want to mess up, if the above didn't work I'd take it to a gunsmith and let him run the risk.
Not worth making a dinged-up mess out of the rings, the 'scope, and the rifle.