Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister, thank you for your important question and for your desire to learn more about Islamic rulings.
No one can tell or decide that a person should go to fire or paradise except Allah Almighty. So we can never decide that a certain person is in hell or paradise except the ones that Allah Almighty or His Prophet (peace and blessings be upon him) told us about. Committing suicide is an enormous sin against which strong warnings have been given. But still the mercy of Allah will admit all believing Muslims finally to His Garden.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states,
Your son is asking a legitimate question; it shows that he cares for his colleague or friend and is worried about his fate, which is good of him.
The best answer you could give him is this:
It is God, and God only, who decides who goes to heaven or hell. We humans cannot decide such matters. All that we know is that His mercy is infinite and that everyone with an iota of faith, even if he was to commit the worst kind of sin or enormity, would be eventually saved from hell-fire and admitted into paradise.
Let us, therefore, unceasingly ask for Allah’s mercy and forgiveness.
Allah Almighty knows best.