We offer two bath towels, two hand towels, two facecloths, two older bath towels for the hot tub and an amenity basket in each bathroom that has four older facecloths, makeup removal wipes, puffs, q-tips, etc...
When we do the fluff, we take away the wet facecloths and replace them, toss the bath and hand towels in the dryer unless soiled and only then will we replace them.
If somebody really needs more towels than that, they can use the hot tub towels which are plenty good still, just have some blotching from the hot tub sanitizer on them.
If we get a guest with a real bad case of OCD and they ask, we'll give them more towels, but don't make a practice of it regularly.
Our county government has mandated that all lodgers not replace towels or linens for four days due to the water situation here. Most of our guests "get it" on the need to conserve, so they usually go overboard the other way to only sparingly use water and their towels and such.
As with many things we need to ask our guests to consider, the heavy hand of government regulation is usually a very safe excuse to limit any behavior if they just won't cooperate out of more rational considerations.
We don't feel like we're cheating anybody out of anything, the perception of luxury or pampering and in this day and age, everybody needs to do their part for the betterment of ol' mother earth, even paying guests at B&Bs.
If that famly had used 19 BATH towels, I'd be concerned, but the overall number of towels used doesn't seem that out of whack.
Our towels and linens are stored in our laundry room which is nowhere near any guest room and expept for the ultra rare nosybody snooping around, we've never had anybody go searching for anything without asking.