It's more than appropriate. Bringing food to mourners is actually a traditional practice, and even alluded to in the Bible. In Genesis we read that Esau sold his birthright to Jacob for a pot of lentil soup. According to the Midrash, Jacob was actually preparing that soup for his father Isaac, who was mourning the death of his father Abraham.
According to Jewish law, the first meal that the mourners eat upon returning from the burial is brought to them by friends and neighbors. This meal consists of round food items, traditionally hardboiled eggs and bread rolls, which symbolize the cycle of life.
In addition, it is an act of kindness to attend to the needs of mourners, as they are usually not up to normal daily activity, and are meant to use the time of mourning as a period of reflection and grieving, without the distractions of ordinary life. As such, food gifts are appropriate throughout the seven-day mourning period. And while platters of chocolates and candies are thoughtful, real nourishing kosher food may be just what the mourners really need and want.
Click here for more information regarding proper protocol for visiting a grieving family.
Malkie Janowski for Chabad.org