Yeah, Morgaine has 94 max HP so now she is down to 55 HP after that big hit. Don't forget Susan, Morgaine does have the ability Second Wind that she can use to heal a little bit as a Bonus Action once per short rest. It's not a whole lot but it's pretty good at an extra 1d10 + 10 HP.
This is a very challenging situation. Hopefully we don't have to use up most of our resources to get through this door. We still have Cyanwrath and friends waiting for us.... Lia will heal only if absolutely necessary against the construct.
If Morgaine's HP is wrong in someway I totally apologize. I don't wish to be any higher than I should be for my level. If the 94 is the max HP she should have, I shall change it to that then subtract the DMG she took from this battle.