Regular capitals can be prevented from warping away by regular tackle (warp disruptors and scramblers). Obviously bubbles and HICs with scripts work as well.
Supercapitals, carriers in triage and dreadnaughts in siege are immune to all EW, which means that regular warp disruptors and scramblers won't work. What will work is bubbles, either from light or heavy interdictors, or scripted HICs (which is what you have to use in low sec where there are no bubbles).
Of course, carriers in triage and dreads in siege can't get away anyway, so you just need to be quick with the points after they come out of siege/triage.
So, TL;DR - the only things that can hold down a supercap are bubbles or scripted HICs.
AFAIK bumping is no longer as effective as it once was since they changed the mechanics of it. Smaller ships now have negligible effect on much larger ships. And bumping won't prevent him from jumping out.