@1Charak2True enough those are also two solutions but you can still be harmed if either of the two see you dissolving into spirit form leaving you open to an attack so you'd have to pick your spots on when you do it and still gtfo with the masters.
Taka is injured already, James wouldn't be strong enough to take on Assassin. Its day time so Jack's not at her full potential.
Metro and run is the best option. Hellsing should be able to last for a fair time with the enemy archer, and besides both Hellsing and Jack are trained in medical. Though one is much better than the other.
Then when you account the nature of Darkened Misty Metro being the ultimate in get away tools (speed reduction & trapping them in the mist, yes please. It'll minimise injury.
Edit: Also Saber can't enter spirit form and that summon was instant. So...