A place to stay near Warsaw University Hospital while Jadwiga receives treatment

My mother Jadwiga has been accepted for treatment at Warsaw University Hospital in Warsaw, starting on Saturday in November. We live 596 km away in a village four hours away, and hotel costs would use up what we have set aside for the treatment itself. We're looking for a room, granny flat or short-term rental within about 30 minutes of the hospital, for 3 weeks. Two of us would stay: Jadwiga and me. We can contribute $40 a week and cook for the household if you'd like. Jadwiga will have some immune precautions, so a clean, smoke-free place would be ideal. A kitchen is a bonus. Thank you. Please ask me anything in the questions section. I'll answer honestly and quickly.