Mmm, that is a little complicated. Did she ever live in US legally over 12 consecutive months? If not, then 100% that her application will be transferred to her local VO for further assessment, and if an interview is requested (most likely, because of her immigration record in US), she has to leave US to attend it. Even she lived legally over 12 months, that is still CIC's discretion to process her VISA at Ottawa, and most time, they won't. If you haven't submit your application, I would suggest you take time to prepare a very strong case to avoid the interview. Since you did submit it, just be prepare for the worst.