your mother should take her to the vet, and they can answer her questions, but for now, how old is the kitten? if it is a kitten, purina kitten chow is good, also purina ONE kitten food, in a canister, if the cat is not a kitten then purina cat chow, or science diet is good, I don't think dog food is good for cats! if the cat is dehydratred then canned food can help if its not real bad.
cats are different, some like to be held and petted, so see is kitty will let you hold her, if she does then give her lots of attention at first, if she wants to be left alone then just put her in her own part of the house where she can feel secure, safe and give her a litter pan, food and water and let her alone for a while then later try to see if she will come out, maybe leave the door open so she can come out if she wants.