As MS mentioned, perhaps site selection should be re-visited... a good source for fresh water plus septic system seems rather crucial to good living to me. If the hall doesn't have these things, perhaps a better site in a more defensible position could be found... and it may well be that people prefer to live in separate houses in a neighborhood rather than altogether in one big mansion.
Does anyone have any thoughts about fresh water for 15 souls? Is there a usable well? What about sanitation? Is there a septic system?
Here are my pics of the Hall again, tell me if I've overlooked anything, but it's a good solid stone-built house surrounded by excellent potential food sources, namely fish from the river, shellfish, seaweed and salt from the seashore, bunnies and birds from the fields and woods, wild berries, fruit, mushrooms and wild honey if we're lucky, good fertile soil all around for growing things, plus plenty of firewood.
The river provides us with fresh water (shall we boil it first?) and do we really need a well? And the river also doubles as a latrine so long as we remember to empty our buckets downstream, or do we need septic tanks/pits?


As for living in a neighbourhood in our own separate homes, it's a matter of preference, but post-apoc cities don't provide as much aforementioned benefits as the Hall would.
Concrete jungles will be pretty bleak barren rat-infested places, especially when the shelves become empty..

"Pray that this will not take place in winter, because those will be days of distress unequalled from the beginning, when God created the world, until now--and never to be equalled again.
If the Lord had not cut short those days, no one would survive.
Be on guard! Be alert! You do not know when that time will come.
What I say to you, I say to everyone: ‘Watch!"- Jesus of Nazareth, Mark ch 13