My mom passed away on September and received social security check $1083 per month. I took care of her and claimed her last year. Why doesn't she qualify this year

So sorry for your loss.   You can still claim your mom as a dependent for 2022 and get the $500 credit for other dependents if you were supporting her in 2022 up til the time she passed away.

CREDIT FOR OTHER DEPENDENTS

https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-credit

You should be able to claim her as an other dependent because she does qualify if she lived with you for the entire year up to the date of her death. . Go back over your answers.  Check the drop down answer that asks if your mother lived with you for the entire year. Here you will say yes because the instructions will allow you to state that she lived with you for the entire year. 

I have included a screenshot to illustrate this. Also check all of your other answers such as did you provide for more than 1/2 of her support. Meanwhile, see if this screenshot addressed your issue. Please note that Wanda is a pseudonym for illustration purposes only.

@budiloo