In Boscombe avoid living in The Crescent, Walpole Road, Churchill Gardens, Palmerston Road area and avoid parts of Springbourne too.
A couple of my friends live round that area which is how I know.
At late night he should just watch himself in the centre of Bournemouth near Horseshoe Common & Lansdowne especially near taxi ranks and basically not take short cuts through the Gardens / by the Beach on his own - but I mean very late at night.
One of my friends loves the social aspect of living in the Lansdowne area of Bournemouth town centre which is near the beach, bars & clubs, restaurants etc.
If not there then I would recommend renting a room in Southbourne near Fisherman's Walk and Southbourne Grove, which is not too far from the stadium; it's near the beach & several pubs, coffee shops.. Plus it's on a quick bus route into town.