well it costs about Euro30 a day for a high quality road bike in that area. A cheap general hybrid with good gears should be about Euro 12 a day. So it depends on the bike and how serious you are. You know Assisi is on a hill?

Is this a guided tour? If not, are you an experienced cyclist? Can you repair a flat tire and handle simple mechanical issues (slipped chain, etc.) on the road?

If it's guided, I would ask whether you need to bring helmets and shoes, and what level of support will be provided (water bottles, prepared snacks, sag wagons, etc.).

Either way I'd ask lots of questions about the bikes and area road conditions. I'd also buy medical/evacuation insurance and make sure it covers injuries that occur while cycling.
This may sound extreme, but we know someone who had a accident while cycling in France, needed surgery and a hospital stay.

These are good suggestions! The tour is guided and is recreational level. I'll ask about gear and look into my insurance as well.

We want to see a few town around....would it be better to rent a car for a day or two?

If I had a choice between a bike or a car I'd select a bike, you get to meet people on a bike but you cruise past people in a car.

And I have the opposite preference. With only two days, I'd want a car to maximize the sightseeing options.