Is what was dreamt after Salatul-Istikhara—of seeing success in the baccalaureate and the presence of a dog guarding the house and moving about in it without harm—merely a dream or a vision, and does it indicate the righteousness of the person for whom the Istikhara was performed and that there is no fear from him, with the aim of inviting him to Islam?

Scholars have agreed to name the sighting of a beloved person in a dream as a "ru'ya" (vision), and the sighting of something disliked as a "hulm" (dream), both of which are creations of Allah. However, "ru'ya" is attributed to Allah as an honorific. What you saw is a vision, and we hope it is good. Inviting a man to Islam is obligatory and carries a great reward. The Prophet, peace and blessings be upon him, said: "That Allah guides one man through you is better for you than red camels."