What should be INCLUDED in service?

Hello,

My C4 GP has had 3rd service done by Citroen dealer in June'17 at 10k mileage (yes, the last owner did only 10k in 3 years).

Now the 4th service is due on June'18, even though its only done around 5k since after the 3rd service (since June'17- last service), what should be included in this 4th service?

Should it be a full service (New engine Oil, fuel filter, oil filter and pollen-cabin filter) or a small service (only Oil change)?

What else, checks should be included in this service?

Thanks