Currently staying with my DGM (I'm hoping that's the acronym for Grandma) and both my mum, uncle and stepdad have used the excuse of 'she's just old she likes to have her way'
I have 2 boys and they are lovely. She has a great relationship with the eldest and honestly hasn't really bothered to try with DS2 (he's nearly 9 months)
I haven't been out since DS2 was born and I made a plan before we arrived with DGM that she would watch DC whilst I met up with some friends late afternoon. I had been gone 20 minutes when she phoned me to tell me that DS2 wasn't playing ball and I should come back (absolutely fine.) when I came back I found that rather than giving him the food I had left out for him, she was trying to feed him purée which he was refusing to eat and pushing away. She told me that she wasn't going to 'feed the rubbish I had left for him' (it was salmon, rice, veg)
She was feeding him jarred chicken dinner something, we are pescatarian.
I had another plan for lunch mid week which I have cancelled as I don't want to have to ask her to have to babysit DS2 again but she is really nit picking at me, I took them to the park this afternoon and she had the hump because getting back at 5.30pm was far too late for two small children 
I'm also not allowed to get into pyjamas until I am just about to get into bed.
When I discipline DS1 (he behaves appallingly towards me in front of her) she tells me to 'shh' and tells me to not be horrible. She will scoop him up or offer him a mint.
We used to have the best relationship and I really saw her as a close friend and when I expressed how her behaviour was making me feel DM, DU and others they have said 'she's just old, she likes things done her way' AIBU to think this is a really lame excuse?!