Yes, SUPPERS is a Scrabble word!

Letter values in Scrabble US: S 1, U 1, P 3, P 3, E 1, R 1, S 1.

Is it a valid word?

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

a light evening meal; served in early evening if dinner is at midday or served late in the evening at bedtime
a social gathering where a light evening meal is served