Is it permissible for a menstruating girl to perform ablution for her grandmother for Eid? And does a pregnant woman continue to pray if she experiences brown discharge?

It is permissible for a menstruating girl to help her grandmother perform ablution, and she will be rewarded for that. As for a pregnant woman who sees a brownish discharge, it is not considered menstruation. The woman must cleanse herself from it and purify whatever it touched, then perform ablution and pray. If the discharge is continuous, she should perform ablution for each prayer after its time has begun, and then pray the obligatory prayer and whatever supererogatory prayers she wishes.