Should I meet my mum, 66yrs age and lives alone

Your mum sounds depressed and depressed people are often quite self-centred and demanding. Often doing as they want just leads to another demand because it doesn’t help the real, underlying problem.

You should only do what you feel comfortable with. In present circumstances your mum is asking you to do something that would endanger her and your family. I would be worried about going to the window because I think she will come out to you.

Having had a close relative with mental health problems one of the hardest things I had to do was admit that I could not help, it was beyond me and that she needed someone with much more expertise and understanding of her illness than me.

When people are ill they are not themselves and don’t always see things clearly.
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What was your mam like before lockdown? Was she controlling? If she was then maybe this is more controlling behaviour but if this is new then you have to take this change into account.

Btw, you have bigger problems than going on a walk with your mom now.

You feel responsible for her and she doesnt seem to have any hobbies or activities to fill up her life.
Are you and your sister her social life?

Send her, or provide a link to, a virtual walk and talk to her on the phone whilst "doing" the walk together.

Don't go there. She is obviously very controlling. 66 is no age at all. Face time, call her, etc., but don't let her bully you into going against your husband, and let's face it, your own wishes. The fact that she has no hobbies or friends is absolutley not your fault. Believe me, i've been there with my own parents, and it really isn't worth it!

It sounds as if your mam is ill. Laying on the sofa all day is not normal behaviour. She sounds as if she needs help. You can't meet up for a walk in the park but you could have a conversation through the window. She can see you and your son without coming into contact with either of you. It may help her if she can see you in person. Do you live far from her?

Seems to me you're sticking by the rules for your own and your child's safety but also for the safety of your Mum.

Is there emotional blackmail going on here?

I don't think you should beat yourself up over your Mum's evident lack of self reliance.

No!
Videochat instead

No! You absolutely cannot! FaceTime her like the rest of the world has to do.