Make ahead meal for 30 people

You may also find some ideas in previous threads here & elsewhere on the web.
If it's not brunch, or you have a main dish in mind, do a similar search using those terms.
brunch for a crowd
https://food52.com/hotline/search?q=brunch+for+a+crowd
make-ahead meals for a crowd
https://food52.com/hotline/search?q=make+ahead%2C+crowd
and from other sites:
https://www.google.ca/search?q=brunch+for+a+crowd&oq=brunch+for+a+crowd&aqs=chrome..69i57j0l5.3140j0j7&sourceid=chrome&ie=UTF-8

I'd serve a spiral cut ham, they are cooked so you can serve cold or warm it in the oven. Another option is a Ham from Honey Baked Hams. Assorted rolls, relish tray with fresh veggies, you can pick these up pre-made at Costco or local grocery, salads from the deli bean, macaroni or potato or all three. Tossed salad is easy using bagged salad. A fruit salad or cut up melons with grapes.No need to try and cook you have plenty going on. Get out your serving bowls, a nice platter for the ham and you're all set. BB

I hope you have a big slow cooker because that is the best option! Of course, you could always borrow a few from friends.

I would make beef bourguignon or some other such dish which tastes awesome when cooked over a long slow heat. You can do all the browning and sauteeing in the morning before you leave or the evening before, and then pop it in the crockpot on low before you leave for church. Everything should be hot and ready when you and your guests arrive home.