it seems to me both are correct. letz see what the native have to say on this ;

In Arabic there are intransitive verbs (verbs that can't have a direct object) like جلس he sat down ex: جلس أحمد Ahmad Sat down (No object) and verbs that are transitive with one object like درس he studied. ex: درس أحمد اللغة العربية Ahmad studied Arabic language and verbs that are transitive with two objects like أعطي he gave ex: أعطي المعلم مها كتابا the teacher gave Maha a book. where مها is the first object and كتابا is the second object. So the right one is to say أعطوا مها كتابا جديدا (Notice the tanween with fat-ha for the object and its adjective) The other form although it's understood but is less eloquent since there isn't really a need for the preposition "ل" .So you can say : أعطوا كتابا جديدا لمها they gave a new book to Maha or أعطوا لمها كتابا جديدا They gave to Maha a new book and it's understood. but I think it's an incorrect use of أعطي so better use a direct object when the verb takes 2 objects Other examples for transitive verbs that take 2 objects : منح - وهب both mean "he granted" وجد he found. for example : وجد أحمد الطريق طويلا Ahmad found the road (to be) long اعتبر he considered : اعتبر أحمد كلامي مزاحا Ahmad considered my words (to be) a joke