Lighting a Candle in the Seven Days After the Festival When the Death Occurred During the Festival

If a father passed away during the festival and a candle was lit for seven days during the festival in his memory, is it necessary to light a candle when sitting shiva after the festival?

There is no need to light a candle when sitting shiva, only during the seven days following the death.

Mishna Berura, Siman 548, S"K 3: "Nevertheless, the candle that is customarily lit all seven days should be lit immediately, and this is not dependent on whether the festival cancels the mourning or does not begin until after the festival, only do not light it where they eat, and certainly not in the room where the deceased is, lest they come to eulogize him, but light it where they do not eat. However, since there is no benefit from this light at all, do not light it yourself on Yom Tov, but through a non-Jew." From his words, it appears there is no connection between mourning and the candle, but the candle is lit in honor of the deceased's soul because "the candle of the Lord is the soul of man," and it is not a matter of mourning law.