Hoglets are independent at around 6-8 wks old and will have left their birth nest to fend for themselves, so it’s perfectly normal to see small ones out and about at night at this time of year (any hedgehogs seen out in the day are usually the ones in need of help.) It would be helpful if your friend could weigh the hoggy to determine an approx age.
It’s extremely unfair to confine a perfectly healthy wild animal, not least because it will have a strong instinct to mate this time next year, helping to keep this rapidly decreasing species from extinction (it’s estimated hedgehogs will be extinct within the next 20 years).
The British Hedgehog Preservation Society state:
HEDGEHOGS SHOULD ONLY BE KEPT IN ENCLOSED GARDENS IF THEY CANNOT COPE IN THE WILD BECAUSE OF AN INJURY (eg AMPUTATED LEG). FULLY FUNCTIONING HEDGEHOGS CAN TRAVEL UP TO TWO MILES A NIGHT IN THEIR FORAGING AND WOULD NOT SETTLE IN A CONFINED ENVIRONMENT. IF YOU HAVE AN ENCLOSED AND ESCAPE PROOF GARDEN AND WISH TO OFFER IT AS A SAFE RELEASE SITE FOR A RECUPERATED HEDGEHOG THAT CANNOT BE RETURNED TO THE WILD CONTACT YOUR LOCAL ANIMAL SANCTUARY OR HEDGEHOG CARER (THE British Hedgehog Preservation Society CAN GIVE YOU AN APPROPRIATE NAME AND CONTACT PHONE NUMBER).
The BHPS, as well as independent hedgehog carers, are always on the lookout for suitable secure gardens for disabled hedgehogs which can't be completely released for whatever reasons. Your friend's garden could be an ideal haven to accommodate such a hoggy in need. You can read more here:
British Hedgehog Preservation Society
In the meantime, has your friend provided adequate sheltered housing for the little hoggy?