Gotta love those old, full of character, horns, and these certainly qualify. The first horn looks like a home made hunting horn that many country folk made. The second one appears to be a late York County, PA horn, shop/factory made. It is a dandy. It may have had a screw tip on it since the spout seems to have threads on the end. It could easily be put back right; talk to Tim on the Forum here, and get his advice. Could be that he can do it for you. The leather flask held shot or balls. Nice combination of horns and shot flask. Used together, no doubt.
Hope that your friend goes back and looks around for the rifle; there obviously was one.
Thank you for letting us take a look. Nice finds!
Dick