This achievement takes place at the END of the level BANDITS. Raising alarms in any of the enemy stations during the level does not matter as long as you complete the last area without raising an alarm.
The opportunity for this comes once you reach a wooden tunnel with fire and skeletons hanging from it. Just past this tunnel, you will see a small door on the right hand side which you will need to enter and rescue the women and children without raising an alarm. This is the only part of the level that matters towards this achievement.
View the best path through this section of the chapter below:
*Posting for Maka91, because he is only playing the digital version.