Mother's Citizenship Interview

My parents had their citizenship interview few days back. My father passed the interview. My mother had been concentrating more on the civics part and never went over the N-400 application. When the USCIS officer asked her about tax returns and other questions she got confused and couldn't answer then correctly as she was scared to answer them wrong. She passed the civics. On the form she was given at the end stated that she needs to be retested again for understanding language.My father has his oath ceremony next week. They are confused whether he should postpone it and wait until my mothers second interview. They don't want one to have a US passport and other one having an Indian passport. Can he reschedule and how he will have to wait to for until next appointment? My mother is OK with her English but her confidence is shattered as the USCIS officer was also not friendly and welcoming. If next time she has the same USCIS officer can she ask for another one? This is allowed at DMV for your driving test if you don't want same person testing you.