A Lynn-based nonprofit that provides housing and other services to people in need is purchasing, renovating, and furnishing six buildings in three cities with help from the state. MassDevelopment last summer awarded Centerboard a $5.9 million bond to support the $6.4 million project. Citizens Bank purchased the bond, a portion of which was used to refinance past debt. The six properties, all of which Centerboard has leased until now, include three group homes — in Chelsea, Lynn, and Melrose — for mothers ages 17 to 22, and a coeducational group home in Lynn for teens aged 14 to 18. Centerboard provides around-the-clock supervision to the residents of the group homes, who are homeless or otherwise in need of safe housing. The other properties are a two-unit house in Lynn for homeless families for which Centerboard provides services as needed, and the agency’s headquarters in Lynn, according to Mark DeJoie, Centerboard’s executive director.John Laidler can be reached at firstname.lastname@example.org.