It's technically possible but vanishingly improbable. If we can't bring 58050 back from Spain considering that locomotive's historical importance (last loco built at Doncaster works) then there's pretty much no chance of repatriating the former DLR stock from Essen.
It wouldn't be able to run at Crich anyway, being high-floor.
There's a case for the London Transport Museum to have something from the DLR (I'm assuming they don't already have an example of any series of DLR units at Acton depot) but with the B23 stock coming in there'll be more viable options available.