My Mother has cervical spondylitis and I am looking for a firm mattress that will help alleviate the pain that she undergoes. Any idea which company has the best firm mattress in the market?

Have you or your mother ever thought about getting the sleep number bed?  From what I see on reviews it is the absolute best of the best! Right now they are actually on sale! You can pay cash or they actually have financing as well!
specifics are:
The Sleep Number c2 Plush-style bed is the original model that launched a sleep revolution. Our breakthrough adjustable air-chamber design lets you change the bed’s firmness at the touch of a button, from pillowy soft to pleasantly firm. A great value, the bed is enhanced with breathable knit fabric and extra gentle cushioning. Available in twin, twin long, double, full, queen, king and California king sizes