I took care of my mother, who passed away from cancer, in my home from May 2022 until Jul. 2023. Does she qualify as a dependent?

[NCperson]

what was your mother's income, excluding social security? 

if that is less than $4400 for the year, then she is your dependent and you can file HOH. 

if that was more than $4400 for the year, she is NOT your dependent, you can't file HOH,  but you can still claim her medical expenses on your tax return (should you itemize)