Answer
This is a deeply sorrowful incident.
The son on whose account this tragedy occurred — if indeed he was at fault in this matter, causing the father to abandon his life in anguish — that son needs serious prayashchitta (atonement) to be freed from this grave sin. And that atonement cannot be done by taking one's own life. It can only be done while remaining alive.
As for the question of the father's soul finding peace or moksha due to untimely death:
First, understand that committing suicide is in itself a sin. Our Rishis conducted deep research on the subject of what happens to the soul after death. First, know that the ultimate destination of the soul is in accordance with its own karma. If a person of meritorious karma dies, that soul goes to the higher realms. Otherwise, it does not.
After the death of the body, generally the soul, carrying the sukshma sharira (subtle body), exits the gross body and hovers in the astral space for some time — or even a very long time — in the preta yoni (disembodied state). The preta yoni is not considered auspicious because all cravings, hunger, and thirst persist, but there is no physical body or organs to consume anything. Therefore, even rebirth is considered a relief of sorts.
For this, contact a good Pandit who can properly complete all the rituals that are performed for 13 days after death, so that the father may receive an "atibahi" body capable of receiving certain offerings.
After this, invite a sincere Pandit and have the Bhagavata Purana recited, so that the father may be freed from the preta yoni — that is, so he may receive a new body. It would be even better if the family members themselves read the entire Bhagavata Purana in Hindi, with faith, over seven or nine days. In that case, no Pandit would be needed.
Beyond this, everything will depend on your father's own karma. No intervention is possible in that. If he was an utterly surrendered devotee of the Lord, then there is no cause for worry. The Lord Himself will bear the responsibility of his yoga-kshema (welfare and protection).