Catelyn's release of Jaime was not exactly authorised by the powers that be, so she's in the doghouse and confined to her father's solar. This seems a bit odd since the powers that be are her son, but he's not around to sort things out.
She first learns that Tyrion is no longer the hand, which is a bit of a problem for her plan since he's the only one she thinks would actually release her daughters. She also knows that Ser Robin is after Jaime, so she's watching anxiously to see if he returns. We already know he won't, of course, at least not with Jaime.
When Edmure returns from battle she learns that he's told Roose Bolton to look for Jaime, which is another worry. On the other hand perhaps this will distract Bolton from Arya's disappearance.
Her father mumbles something about Tansy, from which she deduces that he got Jon Arryn to marry Lysa in return for Tully alliance, which Catelyn sees as a huge wrong even though that seems to be par for the course amongst the Westeros gentry.
She also learns that Robb is injured in battle, but it's only a minor injury. He's probably only lost an arm or a leg, then.
