Sarah Shaw seemed to a good puritan wife. She seemed to love both her son and husband dearly and did her best to close the rift developing between them over Abigail Harkness.
Sarah Shaw died under mysterious circumstances while her husband was in Dormammu’s dark dimension. Her death appeared to be mystical so that means her killer was likely to be either Dormammu or one of his agents or Abigail Harkness.