Why Gazala hates Razia so much?

I dont get the hatred of Gazala towards Razia and why she wasnt at Azaans wedding celebrations? And who is the young man around this mad grandmother btw?

https://www.instagram.com/p/B3PMZ8fhBbZ/?igshid=1mrh45a192lq5

must be because her husband gave the power of bahu begum RB