"غُرْفة اَلْأُسْتاذ مُحَمَّد"
Translation:Professor Mohamed's room
Elsewhere, it was required to say "The professor Rania's room." why not here "The professor Mohammed's room." Is there a rule that I am missing?
if you faced "the professor Rania's room" you should report that because I don't think this is proper English.
You might have been tricked by "the professor's room". When a proper noun is used, 'the' article is automatically omitted. Professor Rania's room; professor Mohamed's room, is correct English.