My mom passed in 2017 I received a disbursement from her annuity. How do I know if the withdrawal is considered an RMD withdrawl?

Did you take a lump sum distribution?

Yes my  half was 10,790.80 listed in box 1 of the 1099-R with 2,029.00 as the taxable amount in box 2a

Ok. If you took the entire distribution as a lump sum then say 'Yes' to the RMD question and continue. I will summarize in an answer below.

I am sorry for your mother's passing in 2017.

If you took the distribution in one lump sum, then you can answer 'Yes' to the RMD question and that All of the distribution was an RMD.