What should I do regarding my oath to seek forgiveness one hundred times whenever I raise my voice at my mother, which I have broken? And does Allah help whoever fears falling into disbelief in this regard, especially with the intrusive thoughts I am experiencing about it?

You must honor your mother and not raise your voice at her, and repent for any disobedience towards her. When using the phrase "كلما" (every time/whenever) in an oath, you must seek forgiveness every time the action is repeated. You are required to seek forgiveness 100 times for each oath. If you forget the number, seek forgiveness 100 times until you are reasonably certain that you have cleared your responsibility. Regarding obsessive thoughts (waswasah), it is recommended to supplicate, distract yourself from them, consult a trustworthy psychiatrist, and avoid dwelling on them.