The best way to catch a bat inside the house is to use a net and gloves. You may find it helpful to turn on a ceiling fan, often the bat will fly around it and be easier to catch in air. Do not touch it with bare hands! Opening a large window can also help aid his exit. If you cannot find it, you may be better off not spending the night in that house. If I go out to look I check along the walls at floor level first, then the closet areas and drapes. Sometimes they will go into light fixtures, but remember do not use bare hands! You cannot risk a bite.