You must not attend this type of gathering, as it is totally impermissible. You should obey your parents at all times, but not when they are forcing you to do haram. Kindly explain to your mother, in a respectful and polite manner, that you cannot attend the gathering because it is impermissible and you fear Allah. Tell this in an affirmative way and not as if you are asking them!

kindly suggest what should be done in this situation: There is a Nikkah ceremony of my brother, where there would be mix gathering and music too may be.I am forced to put on make-up (apply make-up) especially by my mother as it is family event.My father says you obey your mother even if she is wrong.But i don’t want to beautify myself in mix gathering. What should I do?