You can get no load annuities through some no-load financial companies like Vanguard so to start with I'd see how what she is being offered compares with something that comes free of a sales load.
I'd also question that fixed rate, seems pretty impossible to me, which makes me think there is some catch or 'gotcha' that we are not seeing that either brings down that rate, or makes it delusional (they are kidding themselves) or deceptive in some way. In any case it's setting off my 'too good to be true' alarm at full volume, along with the 'shark attack' alarm as well. (I would strongly suspect the 'advisor' is advising the product that makes the most money for him, NOT what is in your mother's best interest)
A fixed annuity is an insurance product, not a security, because the insurance company must credit the annuity holder’s account with the specified interest rate for the contractually-stipulated time period, regardless of market fluctuations in actual interest rates. It is the insurance company that bears the investment risk, which it does by investing the annuity holder’s purchase proceeds in fixed-income instruments that the company hopes will provide sufficient return to fulfill its contractual representations to the holder. THIS is why there is no prospectus (it's not a 'security' they are not required to provide one by SEC) because the risk is entirely with the company. Obviously as pointed out in the comments, the company could easily go out of business (especially of they sell a lot of these and can't find a way to get that kind of return on the invested money). Now, ask yourself, if I was the insurance company, would I be comfortable guaranteeing that level of return over that much time if I intend to make a profit from it, pay sales comissions, and stay in business?
In terms of 'will they stay in business' I'd have a hard look at their ratings, and go compare where that is on the total range for AM Best (they are lowest 'secure' rating, next thing down is in the 'vulnerable' category) and Standard and Poors (4 places down from their best rating, next thing down is 'marginal' followed by 'poor') You might also want to see if you can get any idea of historical ratings, is this company's ratings falling, or rising? Personally, for the amount of money involved, I'd want a company with MUCH higher ratings than these guys.. THEN maybe someone could say 'no risk', but with those ratings? an no, I don't think so!
BTW I'd check over what this bozo (um sorry, that's not fair to clowns) is recommending she do with her own funds as well. For example is he recommending she take something that is already tax sheltered such as an IRA and investing the stuff inside that in an annuity (kind of pointless to 'double shelter' the money, or lock it up for a period of time when she may be required to make withdrawals) make sure you don't see something there that is actually against what is in her best interest and is only done to make him a comission.