It's an Epiphyllum of some sort, I think - one of the "orchid cactus"

there is a very active houseplant forum ..

that huge plant is in way too small a pot ...

and it looks like the pot is filled with dirt.. rather than media ... and that is a watering issue .... of which g ma might have been a wizard using .. but it might be very hard for you to learn.. before you have problems ...

most houseplants are very easy to propagate .. and sometimes its easier to start a new young vibrant plant.. rather than try to fix a very old.. problematic plant... if you do this.. understand.. you are renovating the SAME PLANT... you are not getting rid of g-ma's plant...

i hope it was out in the sun.. ONLY for this pic ... there isnt enough soil for a plant that size to not dry up real fast ..

ken

ps: e.g. if those long bare sticks will root easily ... then they can be cut off.. rooted... and then the old one can just be thrown away ... and if say.. 3 inch sticks will root.. you could make about 50 of them by xmas... and give them to the extended family as gifts...