I would also recommend Wizard-Events at first when it talk about best mice tour operators in delhi.
With events they also deals in Travel industry. Not in India they have organized events at International level and have worked for brands like HCL, HP, TATA, HILTON and more.
You can visit them online at http://www.wizard-events.in/
Call on: 9711479785
Address: 907, Surya Kiran Building, Kasturba Gandhi Marg, Connaught Place, New Delhi 110001