Common scenario and situation leading to similar questionnaire -- Is it plagiarism?
tried to obtain some ideas from other examples for the questions


That has the hallmark signs of plagiarism, although without seeing the original sources and your questionnaire it is hard to give a definitive answer. It is okay to look at other sources for ideas. Paraphrasing is okay also. Copying, or even changing a few words, is not okay without proper attribution. In general it is okay, and often desirable, to reuse an existing questionnaire, or parts of an existing questionnaire, in a new study, but you need to provide attribution to the original questionnaire.

As to the similarity between you and the other student, this depends on if you used her questionnaire for ideas. If you never saw her questionnaire, then you clearly did not plagiarize from her. It is possible that both of you got ideas from the same source, in which case you both plagiarized someone else.

You need to determine if you plagiarized and if you did plagiarize, who you plagiarized from. If you plagiarized from the student, you need to tell her and your supervisor. If you plagiarized from a third party, you need to tell your supervisor. You should also inform the student that your questionnaire contains plagiarism, but that you did not plagiarize her. You should also tell her that you are telling your supervisor.