All of exchanges that i am using, closed their bitcoin wallet for deposit and withdrawal. Some of them want to take my BTC and give me BCC instead. This is certainty and they said on news.
BCC's value is 0.1 BTC at now.
What should i do for holding value of my BTCs in dollars?
Some of them hasn't any option for trading BTC/USD.
Should I exchange my BTC with ETH?
What do you mean by "they want to take your BTC?"
Ofc not, your BTC will remain the same.
They will give you BCH if you hold your BTC during hf.
https://www.timeanddate.com/countdown/launch?iso=20170801T1220&p0=1440&msg=Bitcoin+Cash+Hardfork&font=sanserif