Praying in the house of a mourner is done so as to display regard with the grieving unique in addition to the deceased. Whilst early as 1790, the "Hebra Maarib beZemanah Oheb Shalom" (חברה מעריב בזמנה אוהב שלום) Group was Started so as to provide mourners observing shiva which https://www.youtube.com/watch?v=9jkGrywMWdQ