Like others have said, she needs to start a new citizenship application. In the meantime, besides ESL classes, I would do full immersion at home: speaking English only together at all times, watching TV in English with English subtitles on, reading books in English, limiting time spent with her Spanish-speaking friends, etc. It will be beneficial for her way beyond the interview. Not speaking fluent English (doesn't have to be perfect but a conversational level) will be limiting for her at work and in daily life. She might as well use this opportunity to put in the time and effort to improve her language skills.