So, as Valka losses her grip on reality, she assumes that Hiccup and Stoick have lead the vikings now attacking her ice fortress to her doorstep.
She is of course wrong, but there was no arguing with this incarnation of Valka. Astrid, Eret and the rest of the gang flying up out of the fray and calling out to Hiccup doesn't help ease the tension.
(-And Toothless was separated from Hiccup for some reason, and of course can't fly without him, but he catches up to them all here.)