Apologies, I wrote the post in a hurry. Budget would be up to 200€. I am not currently home, my father will measure it this evening will also ask him about the rims, I know they are Alexrims, bur can't remember currently the model. The problem are mainly the hubs. The bike she bought was an Author trekking, but the lbs went the cheap route on the hubs. They are still the old type, without cartridge bearings, and they really take a lot of effort to turn.
Maybe it would be a better idea to just replace the hubs, and save for a new bike in the future. There are quite a bit of hills where she lives, and maybe an ebike would be more suited for her. Although I was pushing against that.