Since, you have decided against this train, there isn't much to say.
But to decide which train is better, you should give us the options of at least 2 trains.
Elderly people is what you have said but you didn't mention their age.
Also, if they need only LB, then with the amount of rush this train notices, LB is very easy.
Also,its...
more... a perfect over night journey and there is no scope to sit and discuss. Ideally, this would be much better for your elder parents as there would no worry about luggage or WL passengers entering into the coaches.
Also, if you dont have a CNF(not RAC) ticket in another train,SMB Is much better than Sitting all night. At least, you can get a chance to request co-passengers for exchange of berths.
Thanks.