Here are some suggestions for accomodation in Germersheim, all within a maximum of 10 minutes walking distance to the conference site:
Germersheim is a small town and thus does not have large capacities for overnight stays. In case you cannot make an arrangement in Germersheim itself, safest is to go with a place somewhere along the train lines. Speyer, for instance, is still within 15 minutes by train to Germersheim, and also is a popular tourist destination due to its historical importance and beautiful old town. Trains run from very early in the morning until almost midnight, each train ride will be about 4€.