When Does Nabu Come Back to Life?

Nabu appears to be alive in this movie (despite his death or coma in Season 4). He helps the specialists and the Winx fight the Trix and the Ancestral Witches.

Does Nabu return in Season 5?

Nabu was seen alive at the Frutti Music Bar in some Season 5 promotional material but this was not the case when the series aired.

Who does Aisha end up with?

Aisha still does not trust him, but changes her mind after he saves her from a monster. She has fallen in love with him at this point and the two kiss in the last episode. In the fourth season, Aisha and Nabu have grown closer. He asks for her hand in marriage, and she happily accepted.