"a smart and famous mother"
Translation:أُمّ ذَكِيّة وَمَشْهورة
In fact your answer, in order of adjectives, is better than Duolingo's
But maybe this is not why it was considered wrong. Maybe because you typed:
The first letter, Alif, in your answer was without Hamza and it should be with Hamza. However, I also think this should be marked a typo and it is NOT that serious to consider it wrong. All in all, your answer should be fine.