All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
The Muslims should observe the Islamic criteria for family gatherings, whether they take place in houses or restaurants or elsewhere. Some of these criteria are mentioned in fatwa 10463, so please refer to it.
If any of these criteria are ignored, such as the case of having women who do not wear hijaab, then such gatherings are impermissible. It is better in all cases to seat the men alone and the women alone, as this is good and of safer consequences.
Allah knows best.