Q.newly planted moringa bush/tree has some yellowing in the leaves
treatment required?
Most trees will be stressed soon after they're planted (transplant shock) and may have yellowing or dropping leaves, but as long as it's planted in an appropriate spot for the species, it should recover on its own. Here is more information about transplant shock:
https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm
If the tree doesn't seem to be recovering after a few months, check this article for other possibilities:
https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm