A no of posts with suitable answers for the queries on post-retirement employment and stoppage of contribution to EPF are already there in the CiteHR. As such you could have verified them before raising the query.
Anyway, on attaining the age of superannuation fixed in the contract of employment, every employee should be retired from service. Under certain special circumstances like shortage of requisite man power, such employee's services can be extended for some more time or the individual's services may be retained on retainership basis. It is the requirement of any special situation and discretion of the employer and willingness of the employee only. Normally, such retention of services of the retired employees will have a negative impact on the morale of juniors due for promotion as well as indicative of favoritsm.
Regarding EPF, one cannot continue as a member of the Fund on completion of 58 years of age.