This is the Hindu belief that after the death, soul of human being still remains in this materialistic world. Just because of the loss of body (due to death) someone can not detach himself / herself from this world. The pull of Love, kindness, affection for his / her family, friends, relatives etc. and the affinity for the materialistic world prevent him the extreme and ultimate departure. As a result, being a bodiless state that man (without body) gets pain. He wants to do many things but can not. They can not or even do not want to make themselves free from this materialistic world. 'PIND Dan' according to Hindu belief Gives them an ultimate relief and paves the way for their departure to the ultimate world of Peace.
Gaya is extremely Holy place for offering Pinds. Pinds are offered in personalised way on your behalf on the Foot print of Lord Vishnu, on Akshya Vot and beside the River Falgu maintaining proper Hindu religious customs so that the departed soul of the dead persons rest in peace permanently. If someone is dies unnaturally (unnatural death due to accident, suicide, murder or get killed) then his/her unsatisfied spirit can not go to the super natural world (his / her "Atma" i.e. soul do not get 'Mukti' - freedom) and comes to this materialistic world again and again and sometimes try to frighten people in many ways.
Pind Dan can be done all the year but it is better to perform Gaya Shradh or Gaya PindDan during auspicious 18days pitri paksh mela or 7days, 5days, 3days or 1day amawasya with krishana paksh in any month. The 18 days Pitripaksha sraddha or Pitrapaksha mela, is considered most ausipicious days for offering oblations to the departed forefathers or any departed Family members. This auspicious 18days comes in every year in the month of September or October.