Question: Can you mate with just a Knight + Bishop?

I completely disagree. The knight and bishop checkmate is difficult, but not THAT difficult. I guess everyone is different. For me the two bishop checkmate is easy, much like the lone rook checkmate or the lone queen checkmate. I think there are much more challenging endgame forced mates, like king and rook versus king and bishop or king and rook and bishop versus king and rook. Draws everywhere but also forced mates everywhere. Those are much more difficult for me.

Bishop and knight checkmate is a piece of cake compared to Queen vs two bishops endgame.

yes

I used to be able to do it and indeed have done it successfully at least once or twice within the 50 moves in a rated game, and unsuccessfully once where mate would have occurred around move 51 or 52. I wouldn't know how to now. I don't take chess as seriously these days. Two bishops is much easier, comparatively speaking.

My God! Why so many posts on something that can be googled so easily?

Obviously a question of interest to many.

I used to worry a lot about these mates, but then I realized they never happen in over the board play. I'm likely wrong but I think even IM's and GM's would have trouble doing it. It rarely happens, very rarely. You're better off studying other stuff. 

I think you are right in that they never happen over the board. I've seen it twice, once when it just happened and again when I tried to make sure the ending went that way. I remember hearing that it happens an average of twice per lifetime for the average chess player.

So for practical use it doesnt mean much to learn it and there are definitely more important things to study. But for me, it's not about actually winning in that situation. It's about learning or figuring out how the pieces work together. It might be very rare, but it's still valuable information if you want to figure out chess. Once you realize how the pieces work together, I think it's fairly easy. There are definitely much more difficult endgames that only have a few pieces. And I do think most grandmasters and regular masters can handle that endgame easily.

For Grandmasters there's an embarrassment factor too!  I seem to remember there were two Bishop + Knight endings in a couple of rounds in the World Blitz Championship a couple of years ago, with cameras focused in on them as other games had finished.  Even in Blitz it would be a bit embarrassing as a Grandmaster to just move your pieces around for 50 moves and agree a draw.

For us plebs I totally agree though.  I will certainly never spend the time to learn it unless I suddenly acquire an interest in it completely independent of the practical aspect of winning a real game with it.  I did face it once in a Daily game on here, but I don't recall ever having the Bishop and Knight myself.

It will be draw if the person with 2 bishops play properly

2 Bishops vs a Queen sounds like a trivial draw, depending on the starting position, obviously - i.e. assuming you can get all your pieces together before they get forked, otherwise it's not really a Queen vs 2 Bishops ending anyway if it only lasts for 2 moves!

No, it is a forced win, with perfect play, apart from one fortress position. You can check that with tablebases, and one can not argue with tablebases because they are, well, perfect.

Thi is a totaly random position set up by me, which according to Lomonosv tablebases is a win for white. White to move mates in 44 moves.

Interesting!  Intuitively I would have assumed you can just keep your 3 pieces together and keep doing a 'ring around the rosie' type defence, but I guess not. As you say, can't argue with tablebases!

Ok, so I guess this is how you would play out the position. Now what is your point beside showing us that you don't know how to win this difficult endgame?

it win