Lunch, definitely. Drinks, definitely. Maybe even snacks.
A list, definitely. Enough supplies, definitely.
A thank-you note, definitely.
A stereo with a nice choice of music, definitely.
I don't think a gift is necessary, and it might be awkward. It would be for me, if I came to help with this.
And as for reciprocation--especially when it's being organized though a church family (note the word *family*--I take it seriously in regard to church), the way you reciprocate is by being a giving member of the family, even if you never give directly to them ever. If you help someone else in the congregation (drop-off babysitting, maybe, since you're home anyway?; volunteer in the nursery; always launder the kitchen towels; whatever), you are creating the community that is helping you.
You might also consider getting one of those helpers to help instruct your children in how to run the vacuum, how to dust, etc., because sometimes kids respond better when it's not Mom or Dad.