Depends on quite a few factors. I just ran a very, very basic and fast quote. At best health, 65 year old woman could get 200k for 4,577 a year. That could be more than they need/want; or not enough.
The idea is that she could take the full 1,784 a month (21,408/yr) and pay 4,577 a year in her life policy. She'd then net 16,831 a year (again, likely growing with inflation, but the 3% kicker would be based on the full 1,784 a month starting value, not some already reduced amount). Then if anything happened to her, your father would get a tax free (the lump sum option they have now wouldn't be tax free, but life insurance is) lump sum of $200k to do with as he pleases. I choose that amount, as it's roughly the equivalent of 7 or 8 years taxable survivorship had they picked a full survivorship benefit from her pension (with a few assumptions I'm making).
The other benefit that's typically overlooked - lets say your mom takes the survivorship benefit from the pension and has a 20% reduction of her pension to guarantee a promise to your dad if anything happened to her. Lets they say she lives 20 years - that's over $115k of reduction in her pension at that point. Lets say that year your father (the survivor in her survivorship benefit) passes away. She will very likely never get back that $115k of lost pension she's had over the prior 20 years. That's simply money lost. If the same thing happened with the life insurance, she could just change the beneficiary to you and your siblings (if you had any) or anyone else she likes. Or she could just cash the policy in (there would be about $93k of cash value in the policy at that point). Lots of options with the life policy, not so much with the survivorship benefit.
ETA - The whole life would have worked best had she bought it instead of term 10-20 years ago or so. It may still very much work well for her here, but the best way to use permanent life to maximize a pension would be to have the life premiums either end, or greatly reduce when you hit retirement - not start when you hit retirement. With my very rudimentary quote above, she'd be spending ~21% of her pre-tax pension (possibly a quarter of her net pension) on life coverage. That could be a very tough pill to swallow.