I prefer option B, the free home delivery.
I am a nurse and I work long shift, sometimes 12 hours. After work I am very tired and I don't have energy for go to the store. Also on weekend the store is so busy and the lines are too long. With free delivery, I can order on my phone in the break and the food come to my home in the same day. This will save a lot of time for me.
Also I don't have a car. Now I must carry heavy bags on the bus, specially the milk and water bottles. It is very difficult in winter when the sidewalk is icy. Delivery will solve this problem.
The discount is also good, because food is very expensive now. But 10 percent is not very much for me, maybe $10 or $15 in a week. The delivery fee now is $9.99 each time, so I save almost the same money.
So I think free delivery is more useful.