Also I am re-posting what i had posted in that thread. hope it helps you.
In QH they are not celebrating Holi at their house, they have been invited by some Khanna(a Hindu) family to join them for the celebrations. This kind of practice is quiet common in a secular country like India where people of all religion live together in each city, town, village and slum! People of different religion celebrate the festivals of each other's in a community and I am proud of the PH and Gul for showing such religious harmony of India which is under threat nowadays!
This show is set up in a Muslim background just like other shows are set up in Hindu background, the show is not about Islam it's about two families who belong to Islam!