Sec 194J

you say you are sending employees for conference hence the expense is of a travel nature and hence no TDS and the room rent  including food  also does not attract TDS under 194 I as the amout involved is Rs 20000/=

It is basically fees  paid for organizing conference including attending exhibition & site visit.

Is this a bill from the event manager ? If so then get his PAN and deduct TDS U/s 194C

Yes, I Agree with Mr. Sivaram you must deduct TDS U/s 194 C Payments to resident contractors and subcontractors

For Event Manager the deduction is u/s 194 J (Managerial services). However, for each individual payments like transportation, hotel, catering etc., it is u/s 194C.