kids showing responsibility

Dallas • Mother of two 👩‍👧‍👧. Married to an amazing man and baby #3 due in April. Wellness coach- working on my personal trainer degree! Have 4 dogs
Ok I'll try and keep this as short as possible! My MIL has done many things to my oldest daughter that I don't think is far she has also said things to my family that weren't truthful but she does it to make herself look good! Any way me and my husband decided to let our 9 year old ride her bike to school! We only live 4.5 blocks from the school and it's a very small town! My MIL texted me yesterday and said do you want me to take Desi to school? I said no she is riding her bike because she doesn't have much longer to ride it! We live in Iowa so winters suck! She fallowed my daughter for 2 blocks then stopped her and asked if she wanted a ride! Desi told her no I got it! Then my MIL asked if her leg hurt? (My daughter has CP) Desi told her no not really I didn't put my brace on so my leg is tight! She made her put her bike in her truck and made her get in! Then when my husband got off work last night my MIL called him and told him I made her walk and her leg was hurting! I am so made right now I could tell her to piss off! Am I over reacting? My daughter told me this morning she feels that her grandma doesn't want her to show she is responsible and makes her feel like her disability is running her life!   
UPDATE: hey I wanted to give everyone an update on how I handled the situation with my MIL! I wasn't going to make a big deal out of the situation I was going to see were it lead to! But she proceeds to call me the next morning as I'm right in the middle of getting my 3 year old ready for school ( she doesn't like to wake up) so I ignore the call the minute it stops ringing she calls again! This time I answer she asked me if desi wanted a ride I told her no we discussed last night that she wanted to ride her bike! Then she makes a loud noise and tells me that the cold will affect her muscles and if she gets hurt she's coming after me! At this point I am so pissed I'm seeing fire! So I asked her why does she think I'm going to let her get hurt? Why is it she thinks she is my kids mother? I didn't have kids to let someone else raise them! She started yelling at me telling me she has grandparent rights and she will inforce them! Then I proceeded to tell her that she had her shot at raising her kids and she blew it! Her mom raised her kids and she will not screw mine up! And in Iowa there is no such thing as grandparent rights unless the parents are deemed unfit! She hung up the phone on me and. I haven't heard a word out of her since it's kind of nice!