Can my child's mom still claim him even if I filed as head of house hold? He is listed as an ineligible dependent for me, my taxes were approved but not his mom's.

With whom does the son live?

if you are the custodial parent you must give the non-custodial parent a signed form 8332.  Your child's mom must include the signed form with her return so she can not e-file.

You cannot both claim your son.   The fact that his social security number is on your return will eliminate the ability for her to claim your son.   She would have to paper file and then you would have to amend your return to remove your son.   Amendments can be filed, so you could possibly e-file your amendment, but she will still have to paper file her return.   Paper filing her return will most likely delay the processing of her return because of the backlog with the IRS.