not a romantic issue, problem with neighbor

Brandi
This is long, but I'll try to be concise.  My neighbor and I used to be good friends (I was nursing at the time, I think it made me real chill and tolerant.). Anyway, I slowly started to notice how she would ask me to have or borrow something EVERY DAY (toilet paper, tampons, paper towels, glue, kitchen supplies, paint, migraine meds, everything.). On top of it, she would want me to take her kids to the bus several times a week.  (I get my ass out of bed to take my kids, you can too!  It takes 10 min!). She frequently goes to the store right when the bus comes in the afternoon, and ends up asking me or our other friend on the street to get her kids.
Now the caveat.  She has MS.  She has pain in her legs.  She has memory issues.  I don't doubt she is sick, and I truely want to help if she needs it.  But she has become a leech.  Of course, she always offers to watch my kids or whatever and she's happy to loan me stuff, but I'm a pretty independent person.  When I need something, I get my happy ass up and go to the store in the morning and get it.   This woman is a mess though.  On top of all those issues above, she never has meds, never has stuff she needs.  Her meds run out and then she has to schedule last min appointments, or she tries to get one of us to go drop off her refill, or if I have something comparable, she wants me to give it to her so she doesn't have to go.
Several months ago, I ordered some nuts from her daughter's scout fund raiser.  I realized this week that I never got them.  I texted her asking when they will come in.  She told me that she was sorry, but it was months ago.  She offered to give me my money back, but I honestly don't know what I bought.
I seethed on this for like two days because I'm not good at confronting people without going full bitch mode.  On top of everything she annoys me with, she didn't bother to text me and let me know they came in?  Send her daughter over with them?  I live 3 doors down, I would have come got them.  I was just so annoyed, and maybe I'm over reacting a bit because I'm 3 months pregnant, I don't know.
Anyway, she finally asked me what was up, and I explained I was upset that she totally stiffed me on the nuts, and that I wished I could help her with her organization, because I thought it would take a lot of stress off her and help keep things like that from happening. She got offended, told me this big story about how she loses chunks of time and memories, and despite 3 planners she can't keep it all straight.   "Well it's pretty frustrating to be the one living like this.  I'm 36 and I feel like I'm 80 years old with Alzheimer's"
I told her I wish I could do more for her, and I'd be happy to remind her of her appointments and things, and she never responded.
On the one hand, I totally get it.  Her situation sucks and if she is having those memory issues, I can't imagine life is easy.  I don't know what to do about her though.  I feel like she totally manipulated me from talking about the real issue at hand.
I'll be honest, if she wasn't my neighbor, I'd have her completely out of my life.  Her issues go beyond what I've mentioned here...the way she treats her kids, husband, and her dog, her smoking (that's making me incredibly uneasy with a baby on the way), severe retail therapy pushing them farther in debt, personal life choices, etc.  I'm dreading her smothering me when the baby comes and trying to babysit all the time (and I'm not comfortable with that.)
Am I being unreasonable?   Is this just part of the sickness, and she has no control over it? How do I deal with her, and to what degree?  Do I let the nut thing go, continue to take her kids to the bus and loan her shit?  Do I try to set up boundaries?  I do say no as often as I can.  
Tldr:  neighbor with MS is completely unorganized and has overstayed her welcome as a friend.  She stiffed me (not likely on purpose) from her kid's fund raiser I bought from among a myriad of other things.  I don't know how to deal with her.