1. If you see Namit , give him his pen.-Personal Pronoun, Possessive Pronoun, Possessive Pronoun
2. We are enjoying his singing.-Personal Pronoun, -Personal Pronoun, Possessive Pronoun
3. This book is ours.- Demonstrative Pronoun, Possessive Pronoun
4. He has learnt driving himself.-Personal Pronoun, Reflexive pronoun
5. This is the girl who helped me.-Demonstrative Pronoun, Interrogative Pronoun, Personal Pronoun