Sasuke and Naruto combined? They would've been able to defeat Haku easily. Reasons:
1. This is Sasuke's part. When they fought before, Sasuke's sharingan awakened and he was able to figure out the moves, there's not much that Haku can do to stop him from following the moves without having another eye technique or gates. The only reason why Sasuke was defeated by him back then after he gained the sharingan is because he jumped in the way of Naruto. Now he has the MS, but that wouldn't even be needed.
2. This is Naruto's part. Back when Sasuke was basically killed when he was trying to protect naruto, Naruto's fox chakra had awakened. That no longer happens. Naruto hasn't simply awakened the foxes chakra since the Gaara battle I believe. But starting at the end of the VOE battle, the cloak appeared instead which is much stronger. Atm, Naruto would probably be able to control roughly up to three or four tails, and Naruto seems to awaken it more easily than before, and he suffers less penalties. Meaning that as soon starts to defeat them, which is EXTREMELY unlikely, the foxes cloak will activate, and only one or two tails would be needed. But Naruto wouldn't even need this, nor would he need Sage Mode, honestly, he would be able to fight on equal terms alone with Haku without using either of those, let alone with Sasuke.
3. This is Haku's part. Naruto and Sasuke both increased their strengths rapidly in huge steps at a time. And Haku never truly had a master and he probably would never find one. Even if Zabuza had stayed alive, he knows nothing about the use of ice, meaning that Zabuza couldn't even train Haku if he wanted to. With that said, even if he went to the other clan (I forgot the name but it's a weaker version of Haku's clan), he was most likely better at using ice than they were. And his own clan is dead. Meaning that he could only train by himself. In other words, there would be no way for him to increase his strength as quickly as Sasuke and Naruto.
