Does your friend have trees very near the house? Only ask because we do and I was wondering if that is the cause of ours as neighbour doesn't and has no problem with moths. If I'm allowed to say, Lakeland, then tell her to have a look at their products. The fabric and carpets spray if used consistently after having a really thorough spring clean helps with indoor ones but I've had to go the expensive route and buy the wardrobe and draw sachets too. Also keep lavender sachets in cupboards which is expensive but lasts a lot longer.
I'm always on the lookout for ways to keep them at bay and cheap lavender. I can't plant any in the garden, long boring tale.