BRATTLEBORO — Curtis A. Monroe, 33, of Vernon, father of four children, who died almost instantly Tuesday morning in a car-pickup truck accident on Ver non Street, became the fourth victim in highway crashes in the state this year. The 1960 pickup truck he was operating was in a head-on crash with a 1970 Chrysler sedan. He was pronounced dead at the scene by Dr. John R. Malloy, region al medical examiner. The car was operated by Ralph A. Kennemuth, 25, of Mayport, Pa. He and two passengers were en route to work at the Vermont Yankee Nuclear Power Plant in Vernon. Kennemuth was taken to Memorial Hospital for treatment of abrasions and lacerations and passengers in the vehicle. Ray D. Scalise, 45, of Warren, Pa., and Randall E. Wager, 45, of Ontario, Canada, also were admitted to the hospital. Mr. Monroe, alone in the truck, received injuries to chest and head and an autopsy was to be taken to determine exact cause of death.