Get last word in a line using Regex C#

Regex is very powerful but in this case it is like using a sledgehammer to crack a nut. The disadvantage of Regex in this case (as you have discovered) is that there is no equivalent of

StringSplitOptions.RemoveEmptyEntries

although you could use something like

var matches = reg.Split(input).Where(s => !String.IsNullOrEmpty(s));

Personally I prefer the method proposed by _dude_ in Solution 1 but modified to handle empty strings and other anomalies thus:

string lastWord = input.Split(new char[] {' '},
    StringSplitOptions.RemoveEmptyEntries).LastOrDefault();

you can use the Trim function to remove spaces at the end of the string.