First of all is the pub currently a "traditional" pub as I think it would be a business mistake to change it if it weren't as she may lose her "regulars"
If it's not traditional that may be because there is a rival nearby that does it very well and she'd be foolish to try and compete with.
The pub game is HARD going my mum used to do pub management for landlords when they went on holiday etc it's real graft! Adding a change on top of adjusting to that could be exhausting too.
That said, in terms of the menu I would say:
Starters :
Baked cheese always goes down well
Deep fried cheese too love breadcrumbed and deep fried Brie or Camembert with a sweet chutney
Garlic mushrooms
Prawn cocktail
Melba toast and pate
Egg mayonnaise salad
Mains :
Ploughman's
Meat pie (usually steak and ale) with mash and peas
Steak and kidney pudding
Macaroni cheese
Roast
Gammon egg and chips
Sausage and mash
Soup and sandwiches
Soup and chips (prob a purely Scots thing)
@LaurieFairyCake
Must admit I thought:
Chicken in a basket
Scampi
Chips made from potatoes fresh and DEEP FRIED none of this healthy oven baked nonsense
Scotch eggs
Pork pie
All day breakfast with related sandwiches
Shepherds pie (as in actual shepherds pie made with lamb mince)
@TwinklyBranch I was just thinking "nobody's said any puds"
I would say
Sticky toffee pudding
Bannoffee pie
Lemon meringue pie
Cheesecake
Chocolate fudge cake
Spotted dick, jam roly poly, treacle tart, fruit crumble all served with a proper home made custard
Have to agree with the other veggies/vegans such a menu would not be great for us.
These days she also has to be mindful of allergies and religious dietary requirements - this is why so few pubs do this now tbh Because these dishes tend to be quite problematic for these reasons
Knowing my friend, nothing will be from the freezer! She wants to appeal to families but keep things good quality and local/seasonal where possible
This is admirable but...again I wonder if she's any actual experience of running a pub?
Price point also needs to be considered and local tastes
I once worked in a cafe where the new to hospitality owners tried having a fairly...exotic? Menu? I mean this was 20 years ago and some of the stuff they had on the menu is still pretty uncommon.
I was a local to the area and had worked in hospitality there for several years and I thought this would be unsuccessful but they didn't listen to me initially. They also opened in the summer when the tourists were in and some of the tourists were a little more adventurous and they took that as encouragement but when the season was over and the money started to drop I pointed out again that it simply wasn't a menu that would appeal to locals who were quite traditional in their tastes AND didn't have loads of money to spend on eating out (area was very recently recovering from miners strikes etc) they uhmed and ahed then the winter hit and they realised they really needed to be more welcoming and more set up for the local tastes and prices.
Your regular/local customers are your bread and butter that's who you depend on in this industry especially in pubs!
There's a pub in the town I grew up in, has changed hands several times and still serves pretty much the same menu as in the 80's with a few additions. Very popular with especially older locals, my friends from there go most weeks if not more than once a week as they know the menu suits and the prices aren't insane and the staff are up to snuff. I'm 49 so yea it's an older clientele mostly - it was then too. But older folk tend to have more money to spend on eating out
That may be why she's thinking to err towards "traditional" but if it's a change to what the pub is known for that could be self sabotaging.
I'd also advise she "gets her feet wet" before making major changes - people rarely like a new broom sweeping a clean floor!
She could change the menu gradually - keep the popular favourites and introduce her own signature dishes
Toasties is a good call! Used to love getting a toastie in my parents local in the 70's made in a proper breville not this panini grill nonsense and having to watch not to scald my tongue 
but best of all getting this as an eat out option means not having the faff of cleaning the thing!
I'm another saying rather than a kids menu offer a half portion menu - that will appeal to kids and pensioners and also when my own dd was little kids menus were crap and very ltd especially when you have a kid that hates chips and fried food! But I get that was just us but it WAS frustrating not to be able to eg just get her a half portion of pasta as it wasn't on the kids menu! It definitely influenced where we went and spent our money
Re diets - at least put the calories on the menu? I'm losing weight at the moment and eating out IS tricky and I'll admit I'm erring towards chain places as I can look up the calories! Costa and Starbucks have the cals on the price labels on their counters which is very helpful
Off topic but re not finding items online - sometimes it's how it's listed eg "gammon steak" may not return a result (even though it should!) but "gammon pack" or "gammon slices" or whatever would (supermarkets have their search parameters and wild cards etc set up very weirdly!) so sometimes try just "gammon" or go via the "browse" option to get the general dept I find I have to do that sometimes
Please do decent roast potatoes with the roast
I disagree they need to be made non veggie though, I can make perfectly good roasties without meat products and she won't want to have to lose custom by a usually veggie item not being veggie
I love a roast, I simply swap out the meat for a nut cutlet or Quorn fillet or similar, all the rest is naturally veggie and I have veggie gravy. Local carveries to me do veggie roast options, some you don't get anything instead of the meat, some you get something STUPID instead of the meat like pasta or a risotto - with a roast?! Wtf?! - a few do sensible veggie options like nut roast, lentil roast, roast veggie tart, mushroom Wellington etc