Vienna offers many accommodation choices. The following, relatively inexpensive Hotels are in proximity to the conference venue:
Hotel Zipser
http://hotel-vienna.travel/en/
https://goo.gl/maps/GLvVwH5YD3M2
Hotel Alpha Wien
http://www.gerstner-hotels.at/hotel-alpha/index.html
https://goo.gl/maps/yLeX6kiEsPD2