see, what i read/heard was that, for example, if one's dad is a kafir and he ask for a lift to the church, say, one cannot give him a lift but if he wants picking up from church to come back home, one should go.
what kind of favour? it depends whether it is against shariah or not. as a general rule if it is a favour that support their deen then it is not permissible, and if it is just a favour related to everyday life and not contradicting islamic sharia then it would be permissible.
Aslamalikum i just wanted to know that are we allowed to do non muslims favours in Islam? please reply back Walikum Aslaam