Saung Wint A1.1

No, no preposition needed, and both pour and de would be wrong. The infinitive suffices:

Je l'emmène dîner. -- I take her to dinner (lit. I take her to dine). In this sentence, dîner is the infinitive, i.e., "to dine". You could also say, Je l'emmène à dîner. In this case, dîner is a noun.