Dependents Ssdi confusion

Hello. My husband and I are MFJ with my mother in law as our dependent who receives ssdi as her only income. What my confusion is is that I was asked if she earns more than $5050.00 a year. Am I supposed to say YES or NO to that question being that she only receives the SSDI as payment? We have claimed her on previous returns and I don't recall being asked this question. Thank you.