Jenelle Evans' Mom Claps Back After She's Denied Emergency Custody of Jace

Jenelle Evans' mother, Barbara, seems like she's ready to fight tooth and nail to regain custody of her grandson, Jace ... despite a judge denying her request for emergency custody.

According to docs -- obtained by TMZ -- Barbara beelined it to court on Friday ... filing a motion seeking full custody of the 16-year-old, who is currently in a mental health treatment facility.

Sources with direct knowledge tell TMZ ... the motion was filed behind Jenelle's back ... and it was quickly denied.

However, Barbara isn't backing down, telling TMZ ... "It doesn't matter that it was denied, because I'm going to court on March 23rd for a temporary custody hearing. The evidence will be presented then."

She goes on to say Jace’s father, Andrew Lewis, will also be presenting evidence. 

As we first reported ... Jace recently entered a mental health facility following a troubling incident at Barbara’s North Carolina home last month. Police responded to a February 22 call described as a “troubled teen disturbance,” sending multiple officers to the residence.