When a stock splits its underlying options must also be adjusted. In general, this works the same for options as it does for stocks. That is, in a 2 for 1 split, you'll receive double the contracts while the book value and the strike price are halved.
However, there can be issues involving options with non-standard strike prices. Therefore in order to simplify matters, we liquidate the option at the last price. Otherwise you'd have an inactive symbol that cannot be traded or updated. In the end, your account value should be the same as before, except that it will have more cash and the options will be removed.