Don't give up and be strong. Good for you losing that weight. Think how healthy your body feels!

You know you can still eat snacky stuff right?

Don't eat it, if you don't want to. It's just food. If one or two cakes go to waste, she'll probably stop.

Some people, including our family members, can get jealous when we see how well others are doing, maybe the cake is because she's jealous you've lost so much weight? Just a thought. But congratulations on losing so much weight!!!!! That's an incredible amount to lose, well done, OP!

Don't give in to the sugar!

People aren't all that comfortable with change. She might not even realise she's doing it or why, because maybe in her mind you've been working so hard and deserve a treat. Or she thinks you've become too skinny, even if someone is still obese (not saying the OP is, just hypothetically) one could think they look too skinny or not right after they've lost a noticeable amount of weight because you're just so used to how they used to look. Of course one can still enjoy sweets while on a diet, but you'll have to watch the amount you eat. I get the feeling that the mom shows up and leaves the whole cake there, leaving the OP to either eat it all, throw it away or try to unload it on someone else. Even with the discipline to follow a diet, resisting a cake you already have right there is hard. That's why one of the most common diet tips is to get rid of the stuff you shouldn't eat, instead of hiding it away until a craving hit. It is easier to resist driving to the store just for a cookie, than to resist taking one if you already have them in your pantry. Ask her to stop. Maybe something like "mum, I appreciate that you baked this for me, but it is really not helping me keep to my goals". Or if she "just want to celebrate/treat you", suggest going out for ice cream or something, then you could just buy a small scoop instead of being left with a whole cake.

Crangratulations on losing 50 pounds! Mabye talk to your mom about the cakes or give them to someone else.

Since delegating with her doesn't seem to work, you'll have to up the active resistance, meaning either firm, outright "No" as if you were training a puppy, chucking her cakes in the trash while she's looking, and/or not even allowing her into your house until she develops the capability to bring more sensible treats like a fruit basket. It's okay to want cake, but you want to live a long and healthy life even more so. What your mother is doing here can be considered borderline abusive. Stay strong, OP. You can win.

why don't you just say to her that you are trying to lose weight and that eating candies/cakes aren't in the plan ?

Sabotage.