I know exactly what that smell is- it's ingarined damp, caused by drying clothes indoors poorly, for example, this could be heaping wet clothes over each other whilst drying, smoking in the room which they are drying, poor ventilation and poor general care of clothes.
I know it's probably not want to hear, but your boyfreinds familoy do not seem to take care or pride in their laundry.
It's hard to get rid of the smell as it is carried deep in the fabric, the best way to do nthis is to wash the clothes, and double the dosage of fabric conditioner, and allow them to dry, hung well spaced apart, outdoors.
Then when they are dry, and only when they are bone dry, iron them shortly afterwards with a special fragranced ironing water- I use Vapouress.
put the clothes away shortly afterwards.
Alternatively. It could be moth balls- nasty smell- just follow the above porocedure.