Book: Taqwimu Shia (p 287).
Author: Abdulhusayn an-Naysabori
And death of Hafsa and Mughira ibn Shobah are two happy news in this month also.
In this book this misguided rafidi discussed different days during the year, and talks about holidays of rafidah. As you can see death of mother of believers Hafsa (r.a) is happy day for them!