Is it permissible to eat food offered by female colleagues at work who deposit their money in usurious banks?

It is permissible to eat from what is offered by female colleagues who deposit their money in usurious banks. The Prophet, peace and blessings be upon him, was hosted by a Jewish woman, despite the Jews' engagement in usury. If the money is mixed, from both lawful and unlawful earnings, then it is permissible to eat from it. However, if the earnings are purely unlawful or predominantly so, then it is not permissible to eat from them.