The mother of a 4-month-old girl who was found bludgeoned to death six months ago in a Pawtucket, R.I., alley was arrested for the murder of her daughter. State policemen and FBI agents arrested Donna J. Richard, 32, at her father's home in Bloomington, Ind. She is being held pending extradition to Rhode Island. Donna and her husband, Ralph Richard, reported their daughter, Jerri Ann, missing last Nov. 11. Her body was found four days later, and it was determined that she had been sexually assaulted.