Yes, CLOSENESS is a Scrabble word!

Letter values in Scrabble US: C 3, L 1, O 1, S 1, E 1, N 1, E 1, S 1, S 1.

Is it a valid word?

CLOSENESS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a feeling of being intimate and belonging together
the quality of being close and poorly ventilated
the spatial property resulting from a relatively small distance
extreme stinginess
characterized by a lack of openness (especially about one's actions or purposes)
close or warm friendship

Also: parsimoniousness.

Not playable in Scrabble US: MINGINESS, NIGGARDNESS.