DEDUCTION UNDER 80DD & 80DDB

I need a clear guideline on how to claim 80DD & 80DDB together. My mother had undergone both kness replacement surgery this financial year. The cost of the treatment was 5 lacs & no mediclaim support was taken, it was done from a private hospital in Kolkata. Pls. tell me what certificate I need to produce to my employer in order to get tax deduction. She is a senior citizen. Can I claim both 80DD & 80DDB together. I am the only child and my father is retired. Pls. help me out urgently.