She is fully able bodied and not short of money.
She has a hoarding problem, and her house just smells musty. She needs to do more washing basically.
The other day, she babysat for us. When we came back home at night, and opened the front door, we could smell her smell, as it had just filled the house.
But I have no idea about how to even start talking about this subject. I know it should be my husband doing it, but we will all be dead before he says anything.
The smell is a symptom of a bigger problem and whilst it is the part that effects you perhaps the best path for all involved would be to focus on the root of the problem. There are several possible causes of your mother-in-law's behaviour but one I've come across is Diogenes Syndrome (otherwise known as senile squalor syndrome). This condition is characterised by hoarding, a lack of personal care (both in hygiene and eating), a lack of domestic care and, unfortunately, often an inability to perceive this as a problem.
At this point, unfortunately, this becomes primarily a medical problem rather than an interpersonal skills one. My advice would be to have someone she trusts sit down and talk things through with her, this may be you or your husband whichever you think she trusts most. You need to reassure her that you care and are willing to help with every step. Above all you need to have patience - it will be a long slow process full of denial - but it will be best in the long run. She will then need to see doctors who may be able to help (in the case I'm aware of this was a mix of OCD therapy and anti-depressants).
I know your initial desire was only to reduce her smell but it is quite likely that she isn't looking after herself in many other ways you're unaware of.
I had the same problem with my father, sometimes he just couldn't smell that he smells, you get used to it as said in the comments, I told him :
Dad, I love you and sometimes you smell bad, and I don't want people to say that you smell bad, just thinking about it makes me sad. A shower once a day or once every two days wont hurt you, and it will save us some awkwardness. Can you please do that for me ?"
That solved the problem forever. Your husband should talk to his mom and say that's it's embarrassing for her first, and for him. He should not mention that you remarked that too, it may be hurtful for her.
My paternal grandfather always used to smell, and he used to deny the fact that he was smelling. He would never listen to my mom about bathing, or just using some sort of air freshener, but when my dad told him the same thing, he finally accepted it. Sometimes, old folks are unable to smell their own smells, having got used to it.
What you can do about it is that first ask your mother in law to put on some kind of perfume. If she asks why, or says she doesn't want it, just let her know (politely) that she smells, and you don't like it. If she denies the fact that she's smelling, tell your husband to try, and if you still have no success, maybe take her to a doctor whom she's familiar with, and will tell her that she's smelling.
If you can get her to accept the fact that she smells, telling her to wash up, or even helping her out to do it as you wish, might work out better. And, your child won't be troubled by the musty smell anymore.
But be aware that everything needs to be done in a way that your mother in law shouldn't feel insecure at any point. If she starts getting angry, or emotional, just calm her down.
(Although your husband would probably be best for this, if your mother in law is very fond of you/close to you, it's perfectly fine even if you do it.)
One consideration is that if the smell comes back after she's showered and done laundry, it could come from some compounds in her diet that her GI tract is not fully breaking down. If you can smell it (or something unusual) on her skin or breath, that's one possibility.
It would also be helpful to localize the smell to (possibly particular) clothes and/or her body, to identify whether she's generating it or if her clothes have absorbed the smell (regardless of source) and are re-exuding it.
I assume that your husband agrees with you about the problem, but suggest you gently double check that.
One of you has to talk with her. One she trusts more. Most probably your husband. I suggest you better prepare him. My idea is to use a role playing game. Your husband acts as his mother and you have this talk with him. It helps to find some of responses he can get while he has the real talk and be prepared for it.
PS: if you follow my advice you may switch roles. It will give him a rest and probably show some new angles from which to look at the situation. PPS: as always be careful with advice from random people.
I dont advise that you start any conversation related to the topic yourself. The best person to do this is one of her children. First of all, she needs to be aware of the problem otherwise you can't do anything about it. Once she is aware then if she is not willing or cant fix the problem by her own control, then you will probably need a psychology help as for sure this is related to a certain syndrome.
