When considering a patient for TOLAC, trial of labor after C-Section, many factors come into play, from both the mom's side and the baby's. For example, likelihood of a safe delivery depends on the reasons for the first C-Sec and if they are still present in the next case, then it does not look good. For example, I could imagine a mom having her first C-Sec for breech failed version, and the two subsequent babies who presented head down were delivered vaginally without incident. Then, her daughter, once grown up, had a large baby who arrested labor at 6 cm. In the daughter's second pregnancy, the doctor again sees excess maternal weight gain, a larger than average baby, and no descent into the pelvis near term. Those would not be good conditions in which to consider a TOLAC. This is just a hypothetical example, but there are an infinity of others which might cause a doctor to advise her against a TOLAC.
Your daughter is always welcomed to seek a second opinion. We encourage TOLAC in appropriate patients in centers that are equipped to handle it, with 24/7 anesthesia and Ob coverage.
Best of luck !