What is the ruling of Islamic law on offering banquets to invitees in preparation for performing the rituals of Hajj, and what are the evidences for that?

The best guidance is the guidance of Muhammad, peace and blessings be upon him. It was not known in his guidance, nor in the guidance of his companions, to prepare for Hajj with banquets. A Muslim must be wary of anything that leads to ostentation (riya') and corrupts the intention, because Allah accepts only sincere deeds done for His sake. Part of the righteousness of Hajj is to be benevolent to others, so increasing Sadaqah (charity) during Hajj is closer to Allah and more beloved.