After the death of Aishwarya's father Shri Krishnaraj Rai in March, the Bachchan family has been low-key as far as celebrations are concerned.
In fact, Bachchan patriarch also did not celebrate his birthday this year, but had a private get together in Maldives. They also did not celebrate Diwali paying their respect to Shri Rai.
However, they are making an exception for Aaradhya for obvious reasons.