No, the interview and oath takes place ONLY in your local USCIS office in the US. If your wife is away traveling to India, and the interview notice comes in the mail MAKE SURE to contact USCIS by certified mail to request postponement of an interview. If you don't respond, USCIS after 2-3 months will consider your wife's N-400 application abandoned. She will have to apply again in the future.
If your wife is able to do the interview and everthing in is order, she might as well wait and complete the oath, which can take place either on the day, or generally with 1 to 6 months (in some cases). This all depends on your local DO. Some DO's offer same day oath whereas most send an oath appointment letter in mail within 1 to 2 months. Some DO's are backlogged and can take a long time to send an oath appointment letter. Just remember that she is NOT a US citizen until she completes the oath!
