Yes, EMERGENCY is a Scrabble word!

Letter values in Scrabble US: E 1, M 3, E 1, R 1, G 2, E 1, N 1, C 3, Y 4.

Is it a valid word?

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

a sudden unforeseen crisis (usually involving danger) that requires immediate action
a state in which martial law applies
a brake operated by hand; usually operates by mechanical linkage

Also: hand brake, emergency brake, parking brake.