Time out of Academic Environment (Mathematics) Earlier in the year, I applied to some graduate school master's programme in the US and have received a few offers last week. 

My goal is to obtain a PhD. Ultimately, I have two options.


Take the graduate school offer. It is a top 15 programme for mathematics and after completing 1~2 years there, reapply for PhD programmes probably in the US or other places. 
Try to wait two years when I qualify as a teacher. Work with a local professor to try and reapply again.


Bit of Background: 
I spent many years outside of my country during secondary education and also during my undergraduate. After graduation, I had worked as a teacher to try and get my diploma to be a fully-certified teacher. Note, I worked in a country which is not my home country so to speak but I have relatives there and many family connections. This year was supposed to be my contract renewal year and after failing to get into a teacher training programme in the first two years of my teaching job, I had planned on other pathways which was to get back into academia. I had intentions of doing a master's and had made applications before to my home country and UK which is where I did my undergraduate. On those occasions, it didn't work out. 

This time round, I applied to a dozen schools in the US with a good score in my subject GRE. As mentioned before, the school that I am considering is a top 15 school. 

Personally, I want to take option 1, go to the graduate school programme and reapply for PhD but if I quit my job, I have no back-up options should I not be able to complete my master's or PhD. This is a real concern as I have been out of academic studies for three years and despite trying to do some mathematics when I have the time, there is no denying that I will be rusty.

The second option is to wait for two years. If I fully qualify as a teacher, I can always return back should I have to quit. I personally feel that five years out of academic study is quite long but this is something that some people have suggested. Is returning to academic studies really possible after such a long break?

TLDR: Got into a decent master's programme, want to accept it but worried about back-up options since I have been out of study for so long. Can I wait two more years to consolidate a back-up plan in teaching and try to re-enter?
This seems to me like a situation in which it is better to "go for the gold". Delay doesn't sound like a backup plan, actually. If you've been accepted and it is something that you really want to do, then just do it. 

I suspect that it will work out better if you start sooner. If, on the odd chance that it doesn't work out, develop a backup at that point. But being overly cautions now might make it harder to achieve your actual goals. 

Take the offer that seems best to you. Make it work. It would place you better for a later doctoral program than delay would and you have no guarantee that you would be able to advance in important areas if you delay.