The easiest way to go to Nijmegen by plane is flying to Amsterdam (Schiphol Airport). There is a train station right below the airport. A direct train takes you to Nijmegen Central Station in about an hour and a half. As an alternative, you might consider the airport of Weeze in Germany. From there you can use the shuttle service (one-way: EUR 16,- , booking ahead required) to get to Nijmegen.
It is a 20 minutes' walk from the central station to the conference venue. For traveling by bus, you will need a 'strippenkaart' which can be bought at the Bruna and Albert Heijn To Go at the central station. A 'strippenkaart' of 15 'strippen' is EUR 7,60, and traveling inside Nijmegen will cost you 2 strippen. With those 2 strippen you can go anywhere as long as it is within Nijmegen and within an hour and a half. If not sure, please ask the bus driver. The closest stop to the conference venue is 'Waalkade'. Lines 30 (in the direction of Oosterhout), 31 (in the direction of Arnhem), and 80 (in the directions of Millingen aan de Rijn) stop here.
For more detailed door-to-door travel information, see 9292ov.