Termination of parental rights; dispositional determination under N.C.G.S. 7B-1110(a); whether trial court made sufficient findings about children's relationship with proposed permanent placements under N.C.G.S. 7B-1110(a)(5); whether evidence supports trial court's findings about lack of appropriate relative placement under N.C.G.S. 7B-1110(a)(6); whether trial court abused its discretion in concluding termination of respondent-mother's parental rights was in children?s best interests.