A screw through the tread area is not usually grounds for replacement - that is easily and reliably repairable. If in the shoulder or sidewall, the tire needs to be replaced.
As for coming to you, that depends on what the warranty says about road service, but usually the basic warranty requires you to bring the rig in for service. If you have tire coverage on an extended warranty, that will surely require you to bring the coach to an authorized repair service, usually an RV dealer shop. Do you have a separate tire warranty of some sort, e.g. from the tire manufacturer? If so, contact a dealer for that brand.
If you have roadside service, you can get a service call for a flat tire, but you will still need to make arrangements to get the new tire under warranty or the flat repaired. Roadside services usually are not warranty service providers.