@BoxOfDreams
I can't believe anyone thinks YABU. You just happen to have moved in next door to this person, you don't owe her anything. Smile and nod, smile and nod, but keep your distance. I may sound harsh, but believe me I've been there with a needy neighbour. I got to the stage of parking in a different street so they don't know I was home!
This. ^
@honeyikeptthekidsthesamesize I think YANBU to keep shunning her. It's the only way she will leave you alone. You have already been understandably quite aloof, and she is STILL bugging you. Imagine how clingy and needy she will be if you start being too friendly?! And why the F did she have a welcome party for you? What a strange thing to do for someone you don't know! A welcome card and a plant or a box of chocolates would have been nice, but a fucking welcome party?!
I had something similar (some 8-9 years ago,) with a woman in the area I live being clingy and intrusive and annoying. I met her at a hobby group and saw her at the local pub sometimes... I was friendly towards her as I am with everyone, and she saw it as me wanting to be best mates!
She kept coming round to my house if I didn't answer her text within 10 minutes, and sometimes waited outside the house (in her car) if I didn't answer the door. She waited for up to an hour a few times!!! I had to stay hidden! 
And when I started to avoid her/not answer her phone messages/make excuses to not see her, she started telling everyone we know that I was avoiding her. I kept getting asked (by 3 or 4 people we both knew) why I wasn't going around to her house, and why I wasn't answering her messages. They said 'she is really worried about you! 
It was awful, and went on for about a year. In the end I had to actually (sadly) drop the other 3 or 4 friends (well, they were more like friendly acquaintances really, but they were decent company, at the pub and a couple of hobby groups.)
The more time went on, the more they mithered and went on about her, because she kept going on at THEM. I got sick of it. Every time I saw them, the first thing they said was 'have you seen Linda?'
Not 'how are you Dandelion? How's the kids? How's work? How's the family?' Just 'have you seen Linda?' or how's Linda?' One time I said to one of them (whilst smiling,) 'you live closer to Linda than I do. Go knock on her door and ask her if you wanna know how she is!' 
Fuxake! 
tl;dr So yeah, you need to be brutal! Keep snubbing her. You cannot be nice to people like this.