Actually, there is NO safe option on the ledge; everything can be punished directly (well except letting go > float > regrab in perfect execution to stall... but well that can be indirectly punished by stealing the ledge from you... whatever :D).
Well, and if you're really just using the ledge attack and rolls, that's limiting your options yourself. If your opponent has a way to cover both at the same time, you will get punished every time he doesn't mess up his execution.
There's no reason to refrain from using Peach's neutral get up, it's super quick and puts you in a place entirely different from Peach's very far ranging ledge roll.
Throw in some up b stalls, if they do stuff like standing between the places you can end up in and shield on reaction of you starting a animation (to avoid the ledgeattack) and it's starting to be really tough for them.
It's feasible to react to any standard thing Peach can use to return to the stage, so if the people who you played have learned to do so, you're out of luck... but it's more likely that you're just too obvious in what you are doing. E.g. many newer players will react with some sort of attack from the ledge when their opponent moves into the "threatened space". Those sort of things where you react to triggers your opponent deliberately gives you is a very good way of getting punished, he doesn't even have to read you, he can just make you do something instead. So verify that they don't just get to push your buttons.
Also make sure that you're acting as fast as possible and don't do the same thing every time. If you use neutral getup and shield every time, you might not get punished for the getup, but they might just grab you and throw you off again, over and over... and well, wasting frames is obviously never good. They might make the difference between you getting a hit on your opponent or being punished instead.
Also ask yourself whether they get significant punishes (e.g. "you're at 90% and ledgeroll past them and they fsmash you for 20ish percents, causing you to reset into a neutral position on the other side of the stage" is barely relevant in most match ups). Peach on the ledge is super limited, paying a little toll to get back into neutral is perfectly fine. Tbh, if I know that's all my opponent will be able to get in that specific scenario, I wouldn't mind handing it to him every single time.
DJ from the ledge is a fairly intersting alternative. It's pretty risky (you blow your DJ), but you have enough aerial mobility to make it fairly ambiguous when exactly you're going to return, a super far ranging aerial (fair) that can beat lots of things, and a great airdodge (through them or up to the side plat).