Mother’s Day?

I think that realistically we can't all stay in isolation until there is a safe effective vaccine, cure, or herd immunity (which could mean as high as 70% of the population having to have been infected), that could take a year or more. People need to balance the risks - if I were you I would try to self isolate for a couple of weeks before visiting and if that is not possible then follow all available precautions when out and about and while visiting.

She is already seeing you once in awhile, and the neighbor who brings her food. Social isolation is a killer too, and better she see you in her home, where you have already been, than out and about. Honestly I see nothing wrong with having a meal or visit with her , just wear your masks if you have been, and no hugs or kisses.. keep some distance as you say she has a large place. My almost 90 YO mom lives with us,, we are "distancing" in the house, and it is killing her that she can't get a hug or kiss once in awhile. I know that sounds wrong as I work in a hospital,, but she would rather have a hug and kiss than live 5 more years! She'll tell you that! And I have a BFF who works with me,, if I have it she does too if you know what I mean.. she comes over, we stay apart but visit. sometimes outside. Mom lives for this! Just use your common sense, and have a wonderful day!

How do you know:
 "Mom can’t stay sheltered till it’s safer for her to go out again."??

Ask her if she wants to go outside while people are still dying of the virus. Or if she can tolerate being patient, deliberate, and wise.

I might not be the right person to say. lol I'm pretty hard nosed about things and say the more precaution the better. Is there a stay at home order that will be in place on Mother's day in your jurisdiction? I tend to look at that and if there is, then, I'd read it to see how it applies. Of course, taking food and supplies to seniors is always allowed in my state.

Is it possible to sit outside and be a good distance away from her? You say there is a nice view. Perhaps, chat at a distance or even call on your phone and talk with her while a good distance away, if she has hearing issues. That's the only way I would consider it. Even sitting at the other end of a table is risky. To me, showing love is best by keeping the distance. I would view it differently if you have also been self isolating and have had no other contact with others since she has.

I have a pretty good idea that lots of family members will be coming to visit my mother next week, without social distancing. They won't check, they'll just show up with a determined look on their face, like they are sacrificing. They think that shows their love. My mother has been isolating since day one of restrictions. But, they will visit anyway. To me, love is best shown by looking out for their best interest and keeping them safe from covid-19.

I would say as long as you take proper precautions a day out would be great for her.
A nice drive would be great.
For lunch a picnic lunch if you can find an open place where you could sit and talk.
I think that would be the best Mother's Day anyone would want. Not a brunch in a crowded restaurant, that costs far more than anyone should pay. Just time. Time spent in some nice company and nice conversation.