"Before I left I talked to [daughter] about feeding and felt she could handle it without me overseeing. Maybe I gave her too much credit. So sorry!!! We'll work to make it up to you!!"
I am confused because she was still here when the feeding was supposed to happen, so even if she sent her daughter over to do it without her - which I would have no problem with as long as she knows how to lock my door - you would think that she would have asked to make sure it was done.
"You talked to daughter Sunday morning before you left about feeding the cat Saturday night? And she said she could handle it? The day after she was supposed to do it?"
I agree, change the locks. This woman is not to be trusted.