who's 'she', the cat's mother

and his mother

Serves as an intensifier for an inclusive noun or phrase such as everyone, anyone, each someone or all someones.

be mother

To pour out tea for others.

cat's cradle

Any complicated structure that appears to be without purpose.

cat's meow

A self-satisfied person.

like mother, like daughter

A daughter takes after her mother.

look what the cat's dragged in

Used as an ironic acknowledgement of someone's arrival, either jocularly or to imply that they are unwelcome or disagreeable in some way.

mother hen

An outspoken and overprotective woman or person dealing with others' affairs; especially, an assertive matriarch.

Mother Hubbard

Empty.