Trump is not attempting to stop absentee voting, which is what it sounds like your mom does. He's attempting to stop states from using universal mail-in voting. These are two completely separate things.
Here in California, as I assume is the case in many states, there are plenty of people listed on the voter rolls who are either dead, have abandoned California, moved to somewhere else in California, etc., who will be sent ballots at the address used when they registered to vote. Ballots that those who are in favor of universal mail-in voting will tell you are easily identified and rooted out, were they to be submitted, which imo is a dubious claim at best.
Even if you agree with that last claim, consider that California also allows something called "ballot harvesting", which is the gathering and submitting of mail-in voter ballots by third-party individuals, volunteers, or workers (rather than submission by the voters themselves) directly to ballot collection sites. These "ballot harvesters" have no problem with submitting ballots for the deceased, or those no longer living at the address used when they registered to vote, if the vote is for the candidate of their choosing.
Clearly, to anyone being objective, the potential for voter fraud is there. That doesn't mean that it will happen.
