Here are some suggestions for possible accommodation near the conference venue:
Luxury hotels:
https://king-david-prague.hotel.cz/contact/
http://www.hiltonprague.com/ubytovani.html
Nearest hotels for reasonable price:
http://www.hotel-merlin.cz/
https://www.dancinghousehotel.com/en/
http://www.hotelusvatehojana.cz/cs/
https://www.mamaisonriverside.com/
Hostels:
https://www.oldpraguehostel.com/
https://www.hostelpraguetyn.com/