How to produce a good final chapter for a thesis or dissertation
The final chapter of a thesis or dissertation must answer the research questions or give solutions to the research problems which were set out in one or more earlier chapters. (If neither is the normal terminology in your discipline, use 'research themes' or 'foci' or whatever, instead.) The principle is that the final chapter must round off the thesis or dissertation.
It is crucially important to realise that the research questions, problems or themes, etc which the thesis or dissertation addresses need not necessarily be those with which you originally started out - unless of course this was a condition of funding. Research is a journey into the unknown and no-one knows what will be discovered along the way. This may be so significant and interesting that the obvious way forward is to create new research questions etc., framed around them. Or it may be that the work could not be carried out as proposed, for whatever reason, and that alternative research questions or problems had to be developed from a fall-back position.
What matters is that the thesis is a well-rounded and self-contained piece of research that makes a case for certain answers or solutions, etc, as set out in its previous chapters. So make sure that your final chapter does address what earlier chapters say that it is going to, and if necessary edit the earlier chapters to make this happen. It is surprising how many students fail to do this, which examiners always pick up.
If you have any difficulty coming to terms with this advice, read the page on a fall-back position.
The final chapter is also the place for listing unanswered questions or unresolved research problems. Their inclusion should not be couched so as to indicate that the thesis has stopped short without doing what it said it was going to. Instead, merely point out what related research questions or research problems suggested themselves during the work, and that they could profitably be addressed (by someone else) at some stage.
Sections from The Research Student's Guide to Success in the chapter on preparing the thesis / dissertation