ANSWER:

Are male waiters not considered as non mahrams?! 

Of course it is not permissible to be adorned and not wearing proper hijab when these male waiters are around.

Is it permissable to go to marriages applying makeup and wearing expensive clothes where there is segregation of males amd females but is extravagantly decorated? The waiters are males,or should we go in hijab just to maintain the family realtionship?