Is it permissible for us to benefit from the money that my wife’s mother gifted to her, knowing that it is from a usurious loan, and that we intend to buy a house with this money?

Borrowing with interest is forbidden usury. The sin falls upon the lender, the borrower, the scribe, and the witness. One must repent to Allah and rid oneself of the loan by returning an equivalent amount. It is permissible for your wife to benefit from this money after it has been repaid. It is not permissible to deposit money in a usurious bank, as the bank uses it for usury. If any of its returns are received, they must be spent on general Muslim welfare.