Is a mother's obedience obligatory in offering Pepsi to guests, considering the Sharia-based detestation of the drink?

The basic principle concerning foodstuffs is that they are permissible. This drink is permissible. If the mother orders her daughter to serve it to guests, she must obey her, for obedience to parents in what is good is obligatory. The fact that the daughter does not like buying it does not justify refusal.