Talk to General Physician on When To Take Vitamin C 500mg Chewable Tablet For Hypertensive Patient?

1. can my mother take this tablet for general use? this haven't been prescribed by a doctor, we are taking it for general use and strength of immunity by ourselves. is that okay? or should a doctor be consulted? 2. my mother is hypertensive. she takes tenormin 50mg tablet plus amodip 10mg tablet both once in morning and zestril 10mg tablet once in night. can she take this medicine? 3. if yes, when should she take this medicine? in morning or at night? after meal or before meal?

respected doctors, please reply to all questions. thank you.