Are the continuous family problems after a series of difficult events, and the mother's unfulfilled vow, and the actions of some siblings, a result of not fulfilling the vow, or is it magic, or what?

The older brother's spending on his mother and siblings is a great deed for which he will be rewarded, but boasting about it afterward may nullify the reward, as Allah Almighty says: "O you who have believed, do not invalidate your charities with reminders [of your generosity] or [other] injury." (Qur’an 2:264). As for the mother's vow, it must be fulfilled if healing occurs. If she is unable to fulfill it, she may expiate it with an oath expiation. As for disputes between siblings, their cause is the whispers of Satan, and they must be resolved with patience, overlooking mistakes, kind words, and exchanging gifts, as well as avoiding sins and observing religious obligations. Neglecting these obligations causes enmity and hatred, as Allah Almighty says: "So We caused to arise among them enmity and hatred till the Day of Resurrection because of what they forgot of that by which they were admonished." (Qur’an 5:14).