I don't understand why "prends-lui deux" can be a correct solution

Bonjour Jacqui,
«take him two» is the translation for «prends-lui deux». If possible, could you include the question that you are referencing on this and resubmit it
à bientôt

The lesson concerning «lui» in affirmative commands follows:
https://kwiziq.learnfrenchwithalexa.com/my-languages/french/view/3180
I am unsure if this is the lesson you are referencing or not; however, let's look at this example.
Ah, les bonbons. Prends-lui deux. This scenario could be two friends talking and the one with the bonbons tells the other to take two to her brother, whom she knows.

Bonjour Ron. Thanks for the clear answer. À bientôt, Jacqui