Nineteen others were injured in the incident that occurred in Meja area.
The accident spot is located on the Prayagraj-Mirzapur highway.
The devotees who died while travelling in the car belonged to Chhattisgarh's Korba, reported India Today.
The travellers on the bus were also heading to Maha Kumbh.
They reportedly were coming to the holy city from Madhya Pradesh's Rajgarh.