It is most likely the calipers. But frankly, it doesn't matter whether it is the calipers or the hoses. Go ahead and change them all while you are at it. It is no more work to change hoses and calipers than it is to change either one alone. And if you shop it out, none of it is very expensive. We have changed a lot of the calipers that were stuck and a few hoses that were collapsed, but have never seen a master cylinder that was holding the front brakes on.

It is common enough, that I go to a pick-a-part yard and look for a van with re-manned calipers and new hoses. Usually $30+/- will buy it all. That generation of van used 2 different calipers; one for rear drum and one for rear disc. They are easy to tell apart.