All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Congregational Thikr (remembrance of Allaah) after the obligatory prayers is an innovation, so it is not permissible, as it is established that ‘Aa’ishah narrated that the Prophet said: "Whoever introduces into this matter of ours [i.e. Islam] that which is not part of it, it is rejected.” [Al-Bukhari and Muslim]
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So, it is an obligation to express disapproval in a gentle manner to those who do it and clarify the truth to them. If they accept, then this is what is desired; otherwise, it is an obligation to leave the place as the lowest degree of shunning evil is detesting it in the heart which requires leaving the place where the evil is being committed.
As for the mother reading the Athkaar aloud with her children, then there is nothing wrong with that if it is done with the intention of teaching them. Once they learn it, she should stop doing that and remind them that they should read their Athkaar on their own.
Allaah Knows best.