Aha, so Margaret who died 1906 must be the mother Margaret on the 1875 census living with Benjamin. In 1880, she is with daughter Mary and is still 55. In 1892, she is back with Benjamin, age 70.
The marriage that you found earlier was a Mary Jane Watterson married to Robert Weir in 1882. So Margaret Quigley's daughter Mary Jane Quigley must also have married a Weir since she is listed on Margaret's obit as a daughter Mary Weir. Unless it should say niece (I doubt it).
Still betting mother Margaret Quigley was a Watterson by birth and awaiting a reply from Woods regarding the marriage of Margaret Watterson to a Quigley and the subsequent births of Benjamin and Thomas.
