Okay so after wondering around a bit, I finally got it working. Below is the content as of how I loaded nib file from external framework, might help someone in future.
NSString *resourceBundlePath = [[NSBundle mainBundle] pathForResource:@"TheFrameworkName" ofType:@"framework"];
NSLog(@"the bundle: %@",resourceBundlePath);
NSBundle* languageBundle = [NSBundle bundleWithPath:resourceBundlePath];
[languageBundle load];
NSLog(@"The bundle desc: %@",[languageBundle description]);
self.scanManual = [[Scanner alloc] initWithNibName:@"Resources/Scanner" bundle:languageBundle];
Since I was getting (null) contents in first few tries, its a good way of checking of the bundle is getting loaded by keeping NSLog. Thanks again to stackoverflow community