What would you do?

I have 1 ex-batt left out of my original 3.  I will have had her 2 years in April. 

I want to make the right decision for the sake of my 1 remaining chuck.

She is alone and is in a run 3 x 4 meters.  We let her out in the garden when we are there which she loves.

She no longer lays but when she did she got into the bad habbit of eating her eggs

Do I get a couple of companions for her that will hopefully lay eggs but which she may eat and pass on her bad habbit?

What are my options? - I just want Betty to be happy

I would get her a couple of friends, as for the egg eating was she laying softies or were they hard shelled? If they were soft then most of the time they don't put two and two together to eat the other eggs, if they were hard shelled then there are things to try like chilli powder in an egg that should help to stop it.  Good luck

My only problem with the roll away nest boxes is that Betty sleeps in the nest box  and has done so for the past 2 years!  How can I get round that problem?

That is a conundrum as Betty needs some friends but you may well find she does pass on her egg eating habit.  Why not try putting a shop egg in the nest box and see what she does - she may have forgotten about eating eggs or have just got more lazy in old age. Chickens don't react to chilli or mustard so the rollaway nestbox Joy suggests may be the best option.

You need to think about introducing new girls as well.  It is Betty's home turf so she has an advantage there, but if the others lay and she doesn't, she may well end up bottom of the pecking order     The ideal would be a quarantine run but if that's not an option, make sure you have more than 1 drinker and feeder so everyone gets a chance to eat and drink