Well, if you're still reading OP
I think Cassandra had the best response if you want to pursue things -
OP, if I was you I would phone up your friend and be honest
Try to arrange a meet up, and if you are given excuses again, say "Please be honest with me, X. We haven't met up for over six months, and every time I suggest it you find a reason not to. Is there something going on that I don't understand? Are you cross with me or is your DH cross with mine?"
Then stop talking and give her time to answer. Don't fill in any awkward pauses. Don't mention the lack of presents / cards as that makes it seem like you're pissed off about it. Just focus on the lack of contact (as that's the thing that is upsetting you).
If she fobs you off again, say "OK, fair enough, but if there is anything you would like to tell me I'd rather know the truth."
After that, I would take the hint and step back from the friendship
Alternatively you could say nothing, simply ignore their upcoming anniversary and wait for your friend to make the next contact and then let her make arrangements/suggest meeting up and see where things go from there.
And re the Xmas presents, just send them, for crying out loud, just send them. Stick a note on to say who they're from unlike the rocking horses (and honestly, who, apart from doting GP's, actually sends rocking horses as a present.......) and just say "Wow, sorry we haven't managed to hand these over in person yet, still, better late than never!" and leave it there.