Mab is in Arctis Tor, locked down after the attack. That's assuming that LC was fixed in the interval when the crew is out of the house, including Mouse and Bob. Maybe Rashid as Mab's representative. If Harry just fouled it up then of course free will and all that and Uriel can't help. Same thing for Molly. Anybody from the future would split the timeline. So our Harry would now be Harry2. That per Vadderung in Cold Days speaking to paradoxical time travel.