Hello, Islam Mohamed,
( All / Each / Every / Both ) of the musical band is wearing a hat.
Where have you taken this from? None of the possible combinations works. You could say:
- All in the musical band are wearing a hat.
- Everyone in the musical band is wearing a hat.
- All the members of the musical band are wearing a hat.
- Each / Every member of the musical band is wearing a hat.
- Both members of the musical band are wearing a hat.