Gulp watch for a handlebars project
If I understood what you are doing correctly you are compiling index.handlebars using data from content.js and you want to recompile if any of those files changes. Below is a simplified and NOT TESTED example of what your code can look like

// removed gulp-watch (built in gulp by default)
// also removed spawn, argv and batch
var gulp = require('gulp');
var handlebars = require('gulp-compile-handlebars');
var rename = require('gulp-rename');

handlebars.Handlebars.registerHelper('next', function(context, idx, options) {
    if (context[idx + 1]) {
        return options.fn(context[idx + 1])
    } else {
        return "";
    }
});

// compile index.handlebars with data from content.js
gulp.task('handlebars', function() {
    var templateData = require('./content.js');
    var options = {};

    return gulp.src(['index.handlebars'])
        .pipe(handlebars(templateData, options))
        .pipe(rename('indexCompiled.html'))
        .pipe(gulp.dest('.'));
});

// watch for changes in content and index files
// and then run handlebars task
gulp.task('watch', function(){
    gulp.watch(['content.js', 'index.handlebars'], ['handlebars']);
});

// on run `gulp` compile and start watching for changes
gulp.task('default', ['handlebars', 'watch']);