Her paternal aunt puts her money in a riba-based bank; can she accept her hospitality?
Question

                I have a paternal aunt who puts her money in a riba-based bank. We advised her, but to no avail, and she spends on her house from the interest that she gets. When she offers me food and drink etc in her house I refuse her hospitality. This is upsetting us and has nearly led to a rift and conflict between us. What is your opinion?.
Praise be to Allah.Firstly: 
If your aunt 
    has another, permissible source of income, such as a salary from permissible 
    employment, there is no sin on you if you eat her food and accept her 
    hospitality, because what the scholars have stated is that if a person’s 
    wealth is a mixture of halaal and haraam, and they cannot be told apart, it 
    is permissible to interact with him, buying and selling, lending and 
    borrowing, etc. It is also permissible to eat his food. The Prophet  
    (peace and blessings of Allaah be upon him) and his companions interacted 
    with the Jews, and they ate their food, although their wealth was not free 
    of haraam elements, because they took riba and consumed the people’s wealth 
    unlawfully. 
But some 
    scholars say that wealth which is acquired via riba is haraam only to the 
    one who acquires it, and there is no sin on the one who takes it from him in 
    a permissible manner, such as if it is given as a gift or offered in 
    hospitality. 
Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) said: 
Some of the 
    scholars said: If something is haraam because of the manner in which it was 
    acquired, the sin is only on the one who acquired it, and not on the one who 
    takes it in a permissible manner from the one who acquired it, unlike that 
    which is haraam in and of itself, such as alcohol and goods confiscated by 
    force, etc. This is a strong argument, based on the evidence that the 
    Messenger  (peace and blessings of Allaah be upon him) bought some food 
    for his family from a Jew, and he ate from the sheep that was given to him 
    by the Jewish woman in Khaybar, and he accepted the invitation of a Jew, 
    although it is known that most of the Jews deal in riba and consume haraam 
    wealth. End quote from al-Qawl al-Mufeed ‘ala Kitaab al-Tawheed 
    (3/112). 
He also 
    said: As for that which is haraam because of the way in which it is 
    acquired, such as that which is acquired by way of deceit, riba, lying, and 
    so on, it is haraam for the one who acquires it, but it is not haraam for 
    others, if they acquire it in a permissible way. This is indicated by the 
    fact that the Prophet  (peace and blessings of Allaah be upon him) used 
    to interact with the Jews even though they used to consume haraam wealth and 
    take riba. That indicates that it is not haraam for anyone other than the 
    one who acquires it. End quote from Tafseer Soorat al-Baqarah 
    (1/198). 
But if your 
    refusal to accept this hospitality will affect your aunt and make her repent 
    from this haraam action, then undoubtedly it is more appropriate for you to 
    refuse this hospitality. 
And Allaah 
    knows best.