My question is will the end result after 1 year (initial deposit + income) will be greater than if i decide to HODL bitcoin and don't run a masternode ?
Nobody really know the answer to this. People can only speculate.
I want to earn passive income but it has a risk right?
Every investment has it's own risk.
What if DASH price falls after one year and bitcoin price keeps increasing,that can happen? or Bitcoin and DASH price directly proportional in long term?
You will have to assess this on your own. Consider the factors like bitcoin dominance, dash adoption, dash adoption, dash development, and many others.