Mohamed's right - this is the past form of "sneak". The "off" part means "away from there". Still, it's not clear what the context is. "She's the one who... snuck off with a camera" can mean she left her group to take photographs alone, or it can mean that she stole the camera. You can also find examples of "walk off with X", which means "steal X". I guess the other sentences in the paragraph will show you the meaning.

To go somewhere secretly and quietly in order to avoid being seen or heard. Longman Dic.

Here She only can avoid without sin or seen