What is the ruling on my insistence upon my aunt's will not to sell the house to a specific person, and what is the ruling on my vow that I was unable to fulfill?

A will to dedicate a portion of one's wealth to charitable causes must be fulfilled. However, a will to prevent heirs from disposing of an inheritance does not have to be fulfilled, because the deceased no longer owns the money after death; rather, ownership transfers to the heirs. Your aunt's will to prevent the sale of the house to a specific person is invalid, and the heirs have the right to sell it to whomever they wish. You do not have the right to prevent them from disposing of their property, and your vow regarding the house is void because it is a vow concerning something you do not own.