A friend of my wife sends prepared food to us.

Answer

It is not good to eat the food of a faasiqah woman who does not observe Hijaab and who travels without a mahram for no valid and pressing reason. The threat of punishment for such a woman in the Hadith is severe, and she comes within the purview of Allah's la'nat. In order not to offend your wife's friend, accept the food. Then give it away to such poor Muslims who are not concerned about the Deen. In other words they are fussaaq. If such Muslims are not available, give the food to poor non-Muslims without the woman's knowledge. Make dua for her hidaayat.

Although eating this type of 'halaal' food is permissible, spiritually speaking it could be very detrimental. It creates roohaani lethargy in a person.