Carla screamed to her children that she loved them and pleaded them to stay alive. Once the three were on the run and out of earshot, Carla mutters that she doesn't want them to go, but covers her mouth with her hand so that the children cannot hear her last words. The Titan pulls her from the debris and squeezes her in its hand, causing her innards to spew out of her mouth. Just after Mikasa looks away, it devours her as Eren watches in horror.
Additionally, both in the manga and anime Carla states that her legs were crushed by the rubble, but in the anime she can be seen freely moving them while she is being held in the Titan's hand.
That's a good mom