How much would be my monthly fare from Grosvenor Metro station to friendship heights none rush hour?

You can use the trip planner on the WMATA website to calculate the fare.

The cheapest way is getting an unlimited monthly pass at the $2.50 level from: https://www.wmata.com/fares/Monthly-Pass/index.cfm. The unlimited monthly pass non-peak would be $90. And you can travel between any stops under $2.50 with that pass.

Five days a week is about 20 days each month, so 40 one-way trips total. It's $2.50 per trip during off-peak times (not rush hour), so $100 per month. Rush hour trips cost $2.90, so that would be $116 per month.

Thanks for your answer.