More teen mama drama! Jenelle Evans reveals in a preview for the Monday, Aug. 28, episode of Teen Mom 2 that she called the cops on her mother, Barbara Evans, after she caught the grandma drinking while watching her eight-year-old son, Jace.

In the clip, Jenelle, 25, tells a producer that her mom — who is Jace’s legal guardian — wouldn’t let her see her child because she had plans to go out with her friends to celebrate Cinco de Mayo. According to Jenelle, she followed Babs to the Mexican restaurant, where her fiancé, David Eason, took pictures of the 16 and Pregnant alum’s mom drinking.

MORE: Ya Know, Jenelle Evans Didn’t Botha Invitin’ Her Motha Barbara to Her Wedding!

“When David was inside, he saw her drinking wine and David took pictures from far away,” Jenelle explains. “I went in there and I was like, ‘Hey you were drinking and now you’re about to drive?’ And she’s like, ‘I had one sip of my wine. They just put it on the table.’ I was like, ‘That’s drinking!’”

Jenelle eventually left the restaurant, but drove to Babs’ home in Oak Island, NC, to confront her again. However, after several hours of knocking on her mother’s door, Jenelle was never let in. “I ended up calling the police when I was there,” she continues in the sneak peek. “The police came and I was like, ‘I don’t know if my mom is passed out and the kids are there.’ He knocks on the door, she opens it and says, ‘I don’t want her on my property!’”

MORE: Maci Bookout Sparks Rumors She’s Pregnant With Baby No. 4 — See Her “Baby Bump”

Earlier this year, Babs shared her side of the story during an interview with Radar Online. “Jace did not want to go with her,” she told the site. “I told Jace and another grandchild to just hide in the house. She came over and banged on my garage and windows for a full hour. She was going ballistic. I thought, ‘Jesus Christ, she’s going to break my windows.’”

Despite Jenelle’s call to law enforcement, the police deemed the incident a “civil matter” and told the mother-daughter duo that their dispute needed to be handled in court. “This was nothing law enforcement needs to get involved with, it was a custody dispute,” Boiling Springs Lakes Chief Brad Shirley said at the time.

MORE: Chelsea Houska’s Son, Watson, Just Said His First Word!

As TM2 fans are well aware, Jenelle and Babs have had their fair share of ups and downs (but mostly downs, let’s be honest) since 2010, when the Read Between the Lines author signed over custody of Jace to her mom. On May 24, the Brunswick County Clerk of Court in North Carolina told Radar Online that Jenelle and Babs finally came to a mutual custody agreement. While Jenelle didn’t regain full custody as she had hoped, the MTV personality — who is also mom of son Kaiser, 2, with ex-fiancé Nathan Griffith, and daughter Ensley, 4 months, with David — was given more visitation time with her eldest son.

Teen Mom 2 airs on MTV Mondays at 9 p.m. EST.

Love Teen Mom? Be sure to join our Teen Mom Facebook group to chat about all the latest updates and juicy gossip!