What Does My Health Screening Report Indicate?

Hi, my mother (67) health screening report showed a 10 mm endometrial thickness which increased to 11.5 after 3 months. Doctor suggested a D&C and biopsy. After D&C and Biopsy all results came out to be good with no signs of any abnormal cells. Now when she went to follow -up after D&C about a month after D&C doc did a pelvic ultrasound and told the thickness is abt 10 mm and she should remove uterus. Can it be possible to have 10 mm thickness within 1 month after D&C? or is it recommended to remover uterus at this stage? She had/have no symptoms, bleeding at all.