Is it forbidden for men to listen to the tambourine (duff), and if so, what is your comment on the hadith about Abu Bakr al-Siddiq entering the Messenger's house on the day of Eid, finding the Prophet's wives playing the tambourine, knowing that the Messenger was listening to them while he was with them in the house?

Listening to the duff (tambourine) is not haraam (forbidden). There are proofs that permit it for men and women, including the Prophet’s (peace and blessings be upon him) permission for a young woman to play the duff after she had made a vow, and his defense of the two young women who were playing the duff and singing in the presence of Aisha (may Allah be pleased with her) on an Eid day.