The correct answers are The notorious jewel thief was finally sent to prison for ten years. and The repairmen drove to the prison to fix a broken security camera.

We use no article ("sent to prison") when someone goes there as an inmate for the institution's primary purpose.

We use the ("drove to the prison") when someone visits the physical building for another reason, like doing repairs. If the repairmen "went to prison," it would mean they were arrested!