If this was a random man, I would agree with the premis of what sparrowhalk has written.
Random man approaches group of women, puts arm round one of them, tells other six on the dangers of getting home and that this one who he knows vaguely likes to walk the long way home and needs protecting. Very annoying, none of his business. It would be irrelevant advise as I don't think anyone male or female should be walking home alone at night after drinking, nobody would interested group of friends. It is highly likely given the fact it was late at night they were leaving at closing time that the OP and her friends had been drinking.
However, this wasn't a random man, this is a pub landlord - male or female a pub landlord will often feel like they have a responsibility to ensure their customers male or female get home safely, especially those leaving at the end.
They will be used to identifying people who are in a vulnerable state, it may be more obvious to them than other people as there used to be surrounded by people under the influence of alcohol.
They will know who else has been in that pub that night, and they might have their doubts about someone and therefore have become a bit on the alert about who is walking home alone.
Lots of what's if and buts with this thread, but stand by my original view that on the face of it,with the information given that this was a human being looking out for another human being and actually doing their job.
As for the landlord thinking the woman might be attacked by men, No mention of her being attacked just her safety. Her falling over into a bush might have been their main concern, who knows they were just doing their job IMO.