A person is qualified to succeed the tenant under a secure tenancy if he occupies the dwelling-house as his only or principal home at the time of the tenant’s death and either—
(a)he is the tenant’s spouse, or
(b)he is another member of the tenant’s family and has resided with the tenant throughout the period of twelve months ending with the tenant’s death;
unless, in either case, the tenant was himself a successor, as defined in section 88.