Hard to tell by the pics what I'm looking at, but this looks old and like it's a big piece of pine. There might be some concern with maintaining the look. Is there drywall there? Is that pine paneling/planking, or is that molding going around the door? Is the door hing mounted into a dedicated door frame, a 2x4, or something else? Most modern doors come with a door frame that slides/mounts into a door opening framed by 2x4s. For a secure mounting, hinge screws go through both the door frame if there is one, into the wood underneath, in most modern structures, 2x4s. For somthing old, it could be more solid than a modern door frame.
I see a couple of possibilities. The easiest but more expensive is to call someone. But if you are up the the challenge, you just need a solid piece of wood to mount the door hinges into. The molding around the door frame (on the face of the door if there is molding) will have to be removed, prying it off, without ruining it (ideally) because it looks old. After removed, you might see a piece of door frame (3/4" thick) piece of wood that the hinges are screwing into or something else, like a 2x4, or a chunk of wood framing.
If pine paneling/planking runs to the edge of the door, the piece next to door would have to be removed, to get at what's underneath. If there is a door frame, instead of ripping out the entire frame (that goes all the way around the door, with a
reciprocating saw the portion of the frame where the hinges mount and the 2x4 underneath (if there is one) can be cut out and replaced. Sounding complicated?