They are coming at you hard and heavy. They have captured C and B and have your faction pinned up in A. You dont have enough time to get enough people behind them. How would you try to turn it around?
Other than screaming for help, put your head between your knees and kiss your *** goodbye. There's a reason you got holed up in the first place and it ain't going away anytime soon.
I would pray to the devs to implement sticking C4 to troops and proceed to ***** the living daylights out of them.
I wouldn't. Any attempts to hold out against a superior force with no time to maneuver to flanking position and no time for reinforcements to arrive will end in your squad getting farmed. At that point reforming nearby and mounting a counter-attack before they can prepare a decent defense is probably your best option.
Pray to vanu I'm TR dammit, more people means more targets for my more bullets. I'll run hard and heavy right back at them and take as many down me with as I can, trying to focus medics. Then I'll lose because everyone else is sitting in the spawnroom trying to farm kills from safety. Goddamn cowards, I hope the commissar hat comes with immunity to FF penalties because they all need to be shot for treason. Also this entirely depends on where we're fighting. A biolab? A fortified outpost? The Crown? I need to know these things. But mostly it's irrelevant as if I don't have time to pull people in from behind them then that probably means it's almost captured and is already a lost cause.
Do an epic last stand or redeploy and come back in force later. If you're light assault, you have a chance of hiding, waiting till the enemy has moved along and start back capping again though. Should probably buy you enough time to get reinforcements in on your squad beacon.
If you are outta time, well the fight is lost, redeploy with your squad and either setup a proper defense or come swinging back in and take it back.