Dollshouse
I framed my grandfather's WW1 medals in an Ikea deep frame on some hessian with his name, rank and battalion underneath on a gold piece of metal I ordered through eBay.
My husband was left his father's medals but his sister has refused to pass them to him (she says she can't bear to part with them but has everything else that belonged to the parents). They sit in a drawer never seen and we would have them on display where they would be seen and discussed. It is very sad as it has caused a rift unnecessarily.
We are not far from Aldershot where there is a specialist medal shop who have the ribbons in stock. They would also advise on mounting etc.
It may be possible for you to get another set of medals; my Father didn't want his, but long after he died I felt the family should have them. Somewhere on the documentation I'm sure there was a question about 'lost' or 'displaced' medals, and in truth your husband has 'lost' his Father's medals, as he certainly hasn't got them and never will have. It may be a long shot, but if his sister has the originals, which are rightfully his, she can hardly complain if he replaces them.