(c) For the immediate purpose of altering or remodeling such housing accommodation, and the landlord shall fail to start the work of alteration or remodeling of such housing accommodation within ninety days after the removal, on the ground that he or she required possession for the purpose of effecting such alteration or remodeling, of the last tenant whose removal is necessary to enable the landlord to effect such alteration or remodeling of such accommodation, or if after having commenced such work shall fail or neglect to prosecute the work with reasonable diligence; or
(d) For the immediate purpose of demolishing such housing accommodations and constructing a new building in accordance with approved plans, or reasonable amendment thereof, and the landlord has failed to complete the demolition within six months after the removal of the last tenant or, having demolished the premises, has failed or neglected to proceed with the new construction within ninety days after the completion of such demolition, or having commenced such construction work has failed or neglected to prosecute such work with reasonable diligence; or