Attending the Walimah is Sunnat if invited. The feast given by the man after nikah is called Walimah. Answering the Walimah invitation is permissible as long as there are no accompanying haraam acts.
If hijaab (Purdah) is abandoned or any other un-Islamic activity takes place, it will be haraam then to attend such a feast. Such a feast will be ‘the most evil food’.
If the Walimah is held in a public hall where females attend, it will not be permissible to participate even if separate arrangements have been made for the women.
The function which the bride’s parents organise on the day of the marriage is not the Sunnah Walimah.
The simpler the Walimah, the more barkat there is. According to the Hadith, a few poor persons should also be invited. Their presence prevents the food from being branded ‘the most evil food’.