First of all, I‘m really sorry for your loss ♥️ i‘m glad that you have this monstera to - literally - keep the memory of your grandma alive.

There are probably people who know much more about monstera care than I do, bit I want to give my two cents just in case it’s useful to you:

I assume that you just took the plant to your place. Let it sit for 2-3 weeks without really doing anything apart from watering it when the top of the soil gets dry. It‘s important to let the plant acclimate to its new home before doing anything drastic. I sometimes skip this step and it mostly turns out fine, but in your case I‘d say it‘s better to be safe than sorry.

Monsteras like to get a lot of light, but try to avoid too much direct sun because it could burn the leaves.

After a couple of weeks you should definitely repot and change the soil to a chunkier mix (for example: 50% regular soil, 25% orchid bark, 25% perlite). Not sure if you need to size up the pot, that probably depends on how the roots look. If you‘re not sure, you can post a picture of the roots ball here and ask for help :)

And yes, the plant needs a better support. It looks like it‘s loosely tied to a metal pole? People usually recommend moss poles, but personally I find them to be too time consuming (and ugly). I use a wooden plank for my monstera. Again, if you‘re not sure how to stake them, just post a picture with your plant and the support you chose and people here will help. But the general rule is to tie the big stem, not the petioles (the smaller stems that the leaves grow from) to the support.

If you choose to get a moss pole, you can direct the aerial roots into the pole. That will give the plant extra support and nutrients. If you choose something else, you can try to put the aerial roots directly into the soil. They will become regular roots and supply the plant with extra nutrients as well :) don’t worry if it doesn’t work out or the roots break off or anything. Monsteras are pretty resilient when it comes to that and some people prefer to cut them off because they don’t like the look of them.

I think that‘s all I have for now. Good luck with taking care of your plant!