I would absolutely tell mom right now to put her child in their room for every naptime starting today. All your hard work during the week is being undone when she puts him to sleep in the living room over the weekend knowing that someone is there and then back to you on Monday is like day 1 weaning him off it again. There has to be consistency...which is only when things are done 100%. I would also recommend you turn the monitor off for your own sake. How does it help to watch the kid scream? It only gives more focus to the issue which isn't helpful. White noise if you'd like although I have never bothered with it and let them cry their little heart out, just don't go back in. If this is not starting to at least change somewhat, even a little, within a week or so then it's because mom isn't doing the same at home so there is no consistency. Yes it may take a while but I really wouldn't worry about it...let him cry. That is how he will learn to self soothe when he realizes there will be no other option coming to swoop in and do it for him like mama does! Mom sounds like she is the cause of the delay in settling in.