I agree with everyone who said how tasteless this whole idea was from the get go, she needs support, not distraction from grandchildren who don't know her well, and don't know her partner at all, thus won't be able to provide emotional support just by being there. She also doesn't need Anna, who publicly insulted her or Jonathan, who got desperate after Dubai got cancelled and felt the need to come up with a plan B to provide some vlog footage. Because that's all this is to him: vlog footage. It was tasteless to include his smiling mum in the thumbnail of the vlog, like this was some happy occasion/implying he made her happy.
Having to watch your loved one die, unable to help, is the most horrific experience, Jonathan always tries to make a joke out of everything, he can't handle negative emotions at all and always tries to suppress them by making jokes, distracting himself, lash out, and so on. How is he going to manage taking the back seat in this dreadful situation, not being able to get his "applause" for being a clown, not succeeding in making his mum "happy"? Will he ego be able to handle it?
My theory: Anna would've never agreed to this trip unless Jonathan promised her to stay in fancy hotels on the way and once they're with his mum. (how would she be able to go to bed at 7PM in a camper van with the kids all hyper and Jonathan still wanting to drink his wine?). They were going to "fake" it and make it look like they slept in it to look "relatable". The silence on Instagram and lack of vlog on Friday means either one of two things: Trying to stir up interest by making it look like something happened, aka the good ol' playing with your viewers emotions to get them to watch the next vlog to make sure they're ok. Or: it all went belly up quickly, a couple of hours in they realised how a 10 hour drive up to Scotland with the prospect of having to drive it all back again set in and they pulled the plug.