Yes, MIHRABS is a Scrabble word!

Letter values in Scrabble US: M 3, I 1, H 4, R 1, A 1, B 3, S 1.

Is it a valid word?

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

(Islam) a design in the shape of niche in a Muslim prayer rug; during worship the niche must be pointed toward Mecca
(Islam) a niche in the wall of a mosque that indicates the direction of Mecca