Tuna may work, just go easy on that...just a tiny bit.
She's probably just scared and overwhelmed. I would suggest setting her up in one room, with food, water, and litter. Access to the whole house can be overwhelming for a baby. Put the litter at the opposite end of the room from her food, as they don't like to eat where they potty.
One trick that may help is lots of love. Momma cats will lick the top of the babies heads to get them to eat. You don't have to lick her, though LOL
. Just lots of petting if she seems receptive to that (if she's not frightened). I notice that most of my adult cats still get hungry after they get lots of attention...the association never goes away (love/hunger).