Translation:They are so poor that they cannot take care of their children.
I got this sentence seven times in the same lesson (Modals 1, 1), all in the form of a 'fill in the blank' question, with 'nemohou' removed.
You will have to complain somewhere else. The contributors of this course can only add more sentences but they cannot control how the questions for you to answer are chosen. Only Duolingo developers can perhaps control that.