If his INR, PTTK, PT is within normal range, he can be taken up for immediate extraction of offending tooth. Otherwise stop anticoagulants in consultation with treating cardiologist, and extract his tooth after 48-72 hours. For immediate pain relief he can use paracetamol tablet, get his tooth out of occlusion. Get his bad teeth extracted as and when his medical condition permits.
Decayed tooth can be filled by artificial material or it can be first root canal treated followed by cap or it could be extracted which can be then prosthetically replaced by taking support from the adjacent tooth. Treatment depends upon the decayed tooth. Kindly consult a Dentist in person.
Pre medication is necessary before extracting the tooth so as to get rid of any sort of infection present that will hinder the healing process.
So ideally your mother should take premedication which includes course of antibiotics and painkillers for 3 days.