I'm not sure "prendi" should be correct here. "Porta" seems to be take as in carry, which prendi seems to be take as in abscond with.
Lei prende cibo al ristorante (it means she take it and keep it with her, restaurant is the starting point)
Lei porta cibo al ristorante (she has food and leaves it at the restaurant, restaurant is the destination)
You could also say "Lei prende cibo DAL ristorante" but it wouldn't translate the sentence that well anyway.
Please ask me if you have more doubts on this or other matters.