What is the ruling of Islam on an employee attending a musical concert that the bank requires him to organize, and what is the position of Sharia regarding the parents' approval of that?

Obedience to Allah and His Messenger takes precedence over obedience to all people. Therefore, there is no obedience to a creature in disobedience to the Creator. Attending parties that involve singing and other forbidden acts such as intermingling (free mixing) and ostentatious display of adornment (tabarruj) is an act of disobedience. Thus, it is not permissible to attend them, nor to obey parents or the bank in this regard. Furthermore, it is not permissible to participate in them in any way whatsoever.