How to sale property by heirs, whose owners i.e., both parents are dead

CASE 1. the property is in warangal 2. registered in 1971 in warangal sro 3. property is on name of mother 4. both parents are dead 5. parents purchased property in 1971 6. there is no will executed by both parents 7. parents has a son and daughter QUESTIONS 1. now the son and daughter wants to sell property, so how could they sell the aforesaid property 2. what are the documents required before selling and after selling, to ensure a smooth, legal and strong/perfect property sale and purchase, without leaving any loop holes which led seller/purchaser from future problems 3. do son and daughter required to transfer property as gift deed on their names before selling to others waiting for valuable feed back thanks in advance for lawyers who responds