Answer
(Fatwa: 1071/603/D=1432)
(1) If most of the income of your tenant is haram, you should avoid eating and drinking at his home.
فان كان الغالب هو الحرام ينبغي أن لا يقبل الهدية ولا يأكل الطعام (هنديه: 5/342ظ كراهية ، ضيافات وهدايا).
However, the rent that he would pay shall be halal for you.
(2) If your uncle and his son live together and most of their combined income is halal, then you can eat with them, otherwise it is better to avoid eating and drinking there:
أهدى إلى رجل شيئاً أو أضافه ، ان كان غالب ماله من الحلال فلا بأس (ايضاً).
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband