Tomorrow will be the 3rd time MIL has come to babysit for us since our son was born, hes 7 months.
The 1st time dp and I went to ikea and when we returned she was prattling on and on about applying for child tax credits, all about how wonderful sil is eligible for them but doesnt claim - good for her, thought it was an odd topic but she is odd 
so the next time she babysit upon our return she was now gabbering on about which local hospital is the best to go to, she didnt like the one i gave birth in and made it well known that it wasnt as good as the 1 her friends daughter went to, so again im thinking what on earth is she on about. Then after she had gone i opened a drawer in my bedside table only to find my next hospital appt check up letter was in there and it was clearly obvious that she had gone through it while i was out. I find this just really odd i know shes really nosey but to go through of all the things in the house my bedside drawer i just found weird. She has mentioned other things that have made me think how does she even know that but having put 2 and 2 together its clear shes snooping around while were out. I love her for coming to babysit, shes giving up her time but that doesnt mean come in and go through my things does it!
I mentioned it to DP nad he said yep she always used to do it to him and his sister growing up and in fact continued to clean their rooms up until the ages of 21 and 24 when they finally left home (believe me ive shared my views on that alone since i found out 
).
so aibu to write a note something along the lines of "get out you nosey old cow" on a piece of paper. or something a bit more dramatic like some retirement home brochures with her name at the top 