Telemachus does not wish Odysseus' identity to be revealed to his mother. Thus, he sends her away at an opportune moment, realizing she's getting a bit too big for her britches. He does not want his mother influencing the events to come in any way.
the definitions for quantity are "The amount or number of a material or immaterial thing not usually estimated by spatial measurement. The perceived length of a vowel sound or syllable."
