For the soiling in the night you could put a few puppy pads down if there's an area she's likely to go in, like by the by the back door or something. I agree with Clare about the time to make the decision, if Molly gets to a point where she is in pain or not able to generally enjoy life then that will be the time to think about it. As for the smell, I'm sorry I don't know!

Would your sister may be know what to do for the smell. I think you said She works for the NHS they must get similar smells.