In May 2006, Dad Grants a Life Estate to Mom

In May 2006, Dad grants a life estate to Mom, with a remainder interest in daughter, Sally.In June 2006, Mom sells her life estate to Bob who dies in June of 2007.Mom dies in October of 2009.Sally claims she has a right to the land after Bob dies.Does she?

A) No, it goes to Bob's heirs until Mom dies
B) No, it goes back to Mom
C) Yes, since Bob's life estate ended
D) No, it goes to Mom's heirs