If it’s a social landlord (I take this as meaning council) they should be allowing people to feed wildlife. I had an annual visit from my social landlord a couple of weeks ago, and they were delighted that there are hedgehogs in the area, and said if I vacate the property they will let the new tenant know (all though that won’t happen unless I die).
If it’s a social landlord, then I think you should write to a wildlife organisation and ask if you can get any advice on how to challenge your landlord – or even write to 10 downing street, (they respond to every letter) and then give the response to your landlord.
If it’s a private landlord, I doubt there is much you can do, but with social, I think you’d be able to appeal their decision providing that you put a strong case forward.
Hedgehogs are are protected species, so the council should be more lenient about tenants looking after them.
Where I live, my neighbours always ask me how the hedgehogs are, and want to know where they are nesting – but they aren’t interested in feeding them and staying up half the night to catch a viewing.
I guess if a neighbour complained, then that could be a valid reason as to why they aren’t allowing you.