Can I give Marie biscuits to my 9 months old son. Is it gud for him?

It's definitely not "real" meal material nor is it a good nutritious snack option. There are other snacks out there that are wayyyy healthier and tastier than Marie biscuits. But for taste's sake, why not? You can try mixing the biscuits with baby's milk and giving it to him or her as a tiny snack.