What are b&bs shit at?

If it has a garden I'd recommend some kids activities outdoors, simple this like hop scotch chalked on a garden path or similar. Also I think for families quite a lot of value is flexibility with food and drinks arrangements. E.g. provide a fridge so people can store some milk in there or facilities to heat baby food or whatever. I realise it's a B&B not a restaurant but these practical things make a difference with young kids.

Also, wildly specific and not necessarily a selling point but always a welcome addition is decent tea and coffee making facilities in the room and some biscuits.

My DC are early risers so being able to sit in bed with a coffee and them eating biscuits is a nice slow start to the day.

The rooms actually being big enough to accommodate a family. So many places we stay the extra beds are shoehorned in making it awkward to spend time in the room if we wanted.

You can get a vibe from photos if a B&B isn’t really geared up for families but it’s hard to articulate. If there’s lots of ‘stuff’ about, that toddlers or kids would be drawn to fiddling with while the owner grimaces on, you know it’s not really family friendly.

Well maintained board games, puzzles etc is always welcome.

A decent kids menu too.

The trouble with marketing it as kid friendly is that he will then probably lose his elderly guests. As I get older “adults only” is one of the biggest draws for me when booking holiday accommodation.

Having said that if he does want family friendly I think the first thing would be to ensure there are enough beds in a room for families. If any of the rooms are big enough to genuinely fit a family of five that would be a bonus (so many families with three kids find it hard to find accommodation without booking two rooms). I don’t know if it’s still a thing in B&Bs to expect guests to be out most of the day but obviously with kids you want to be able to spend time in your room if kids need a break. Any kids’ equipment like high chairs needs to be absolutely spotless and breakfast options need to be suitable for kids. Can he suggest local babysitters he can vouch for?

I’m not sure I would ever have been drawn to B&Bs for family holidays tbh. We certainly never took our kids in 25 years of family holidays. I either wanted self catering so we could relax and do our own thing or a hotel with all its facilities.

If he's not getting bookings then looking at what the competition is doing is important, they're clearly offering something he isn't and its much quicker and more effective to look at his b&b and do a quick comparison to others.

If families are going elsewhere then there will be clear reason why - an immediate appeal which he doesn't have - supplying extras is unlikely to change that if he's not getting the fundamentals right.

I would be put off by a b&b with toys for children, it'll disturb the peace of other guests. Board games and books are always excellent to keep and needn't be limited to families with children.

Things the ones I’ve had to stay at could have improved:
Soundproofing the rooms
Minor decoration quality issues such as scuffed skirting boards, mould on window frames
Decoration too much to the owner’s taste
Owner wouldn’t leave us alone at breakfast
Owner needed to know exactly what time we would arrive and we didn’t know, but wanted to be able to arrive at some time between 3-6pm without having to negotiate this in advance
Child-specific, not having a fold out bed in the room for the DC would be a deal breaker

Which town?
Things that put me off booking are dated and/or cheap furnishings.

Are bathrooms shared?

What's the competition like?

Would help if you link to the b&b