If a house is "under guard" it means that a guard is posted at the house. Alternate translation: "in a house and put a guard there" (See: [[rc://en/ta/man/jit/figs-idiom]])
This means that they were not allowed to leave the house. Alternate translation: "they were shut inside the house" (See: [[rc://en/ta/man/jit/figs-idiom]])