hi welcome to hcm.first she take complete bed rest
.yes these medicine which prescribed by your doc which all for maintenance of pregnancy
.see batter reason tell by doc because on these history perfect reason described which is difficult but tell her don't be too much tensed .there are reason like placenta privia,any kind of erosion in cervix ,folic acid deficiency
etc.but if her sonography
normal then do continue these medicine and regular follow up your gyna.