Talk to Gynecologist on Miscarriage Problem

my sister have one early miscarriage just after she is again pregnant .... her last period date was 19-9-22 her beta HCG value was73.8 she was also facing spoting doctor treat her with an injection and advised her to do beta HCG again after 48 hrs then at 21-9-2022 her beta HCG value goes down i.e now has given her medicine to abort...I want to ask that what does that mean if HCG value is going secondly is doctor advising her rightly?should we use medicine given by doctor for also advise her serum TsH test its value was0.91(UIU/ml)Is that normal ? and HBA1c value 5.4%