Answer: guilty of being an accessory to robbery.
Explanation:
If Bill robs a store without Andy's knowledge, but later tells Andy, who allows him to stay at his home so Bill won't get caught. Andy is guilty of being an accessory to robbery.
An accessory to a robber is simply an individual who isn't aware of a crime before the crime was committed but later knows about it after the crime has been done. Such individual after knowing then helps the robber to keep the secret. This is what Andy has done.