You can deliver a speech on Prominent leaders such as Dr. APJ Abdul Kalam, Swami Vivekananda, Mahatma Gandhi etc.
It is very good topic at which you can deliver a speech like cure from pollution, tree planting, our duties toward environment etc.
You can give a speech on 'My Mother'. Mother is everything in our life, you can talk about how mother helps us and we should be grateful to her.
There are so many issues that exists in our society like dowry, expenses in marriage etc. You can discuss the solution to cure.
You can tell about the solution of how we can clean our home, village and school etc. And about the cleanliness of our body.
The most expensive thing is time that can't be bought. You can speak about the importance of time in one's life.
You can deliver speech on importance of yoga and exercise in our life. To stay fit we should do yoga everyday.