Is the canon eos 300 (film, not digital camera)a bayonet fit or a screw fit for the lenses?

It's a bayonet fit, and it will only accept the Canon EOS (also known as Canon EF) bayonet mount.

The camera is bayonet mount for lenses, but the front of the lens should have a screw mount for filters.

Bayonet mount, specifically Canon EF mount.