While reading some of the other comments, for those who say she should have warned or protected gramps, realistically that would actually be pretty hard for her to achieve. We don't know if she ever knew what his assignment was in the army and where he was based and even if she did initially, after she was demoted it was likely her access to troop information and their movements would have been limited. After she fled and betrayed her country, she would have then had zero access to information on who was where. In that time period he could be anywhere. In other words finding him among hundreds, likely thousands of soldiers would be the equivalent of a needle in the hay stack. As others pointed out, she wasn't in a position to be asking favors from her new alliance, and if she was discovered trying to send messages to Ehas herself, they would probably kill her right there assuming she's a double agent. Moreover, even if she knew where he was and she managed to sneak off a message, you also run the risk of someone else in Ehas discovering the message which would have sabotaged her plans, led to more battles, reduced her credibility and still might not save the old man.
I'm sure she wishes he was alive, but it's something out of her control. Plus Paulina and gramps knew that with any war its a battle in itself to stay alive yourself, I don't think they had any assumptions the other would be able to come to their rescue.