Complex sentence: Haymaker was wearing a neck brace due to an injury and bandages as part of a Halloween costume, startling her and causing her to she retreat inside, lock the door, and tell her husband Rodney to get his gun.
Split into simpler sentences: Haymaker was wearing a neck brace due to an injury and bandages as part of a Halloween costume, startling her. She then retreated inside, locked the door, and told her husband Rodney to get his gun.