The only way i think atm is to restart your game then try the escape again. Usually fixes it.

Okey thnaks

Did the lord you were trying to help escape dislike you (had a negative favor rating towards you) prior to taking the mission to help them escape? If so, that's your problem. It's not a bug.

Just cause their wife sent you to save them doesn't mean they still don't hate you. I've done this many times in Warband; once outside the jail they instantly try to cut your head off. Best option is to run away from them and kill the guards while staying away from the idiot your trying to save, and hope he doesn't get knocked out again by a guard before you can kill them all.

Sometimes it does glitch and doesn't let you win after you defeat all the opponents cause it still considers the idiot an enemy too, in which case you either kill him and fail the mission or reboot/reload and try again with hopefully better results (ie. no glitches).