Mother has blood clot in left knee after double knee replacement

My mother is 55 years old and had double knee replacement surgery 13 days ago and was in the hospital after her surgery followed by a rehabilitation clinic and we'll be bringing her home tomorrow.

Unfortunately, she was diagnosed with a blood clot in her left knee yesterday and is now on blood thinners.

How bad is this? What advice would you give to her? She hasn't been assigned a hematologist yet for some reason despite her rehabilitation clinic being top notch. Should she get one?

Both her legs are still quite swollen with blood, her mobility has improved significantly though.

They want her out by 10am tomorrow despite us hearing this news today!!?? My mother prefers to come home but I wonder if she needs some kind of medical monitoring? My biggest worry is something happens when everyone is asleep or that we're unable to save her in time if it turns into Pulmonary Embolism...