Why are festivals not celebrated after the death of a family member for a full year? What is the reason?
It takes one year for soul to reach Yama Loka after death. The path to Yama Loka is full of difficulties so to make the journey easy for the departed soul, certain rites have to be performed for the entire duration of the travel. After death, soul remains at familiar places like home for 10 days. On the 11th day, it starts its journey towards Yama Loka.
Swami Sivananda had given a detailed account of the journey of soul:
The soul is fully embodied on the eleventh day. It starts on its journey to the judgement seat of Lord Yama, the God of death. It takes one full year from the time of death to reach Lord Yama’s place. The path is beset with obstacles, distress and difficulties. The man who has done the most wicked deeds suffers more. But the difficulties can be removed and the journey be rendered easy and comfortable by the oblations and offerings given by the son of the deceased during the first year of the soul’s journey and by feeding pure and learned Brahmins. The son should offer rice-balls to the father, without weeping.