<human>: Give me a shortened version of the text

This is my first time in the personal finance subreddit, so please pardon me since I'm still green behind the ears. My mother recently passed away at the age of 60, leaving my father (the primary beneficiary, aged 60) a decent pension income, decent life insurance benefits, and her retirement accounts. 

She has a 401(k) and as well 2 x 457 accounts (from different employers) and one 403 (a) account, all amount to about $600,000 (from what I understand it is all qualified money). 

My father (65y) and I (I am the only child) are not savvy about retirement options, but so far what we see is he has a decent income from social security as well as from the life insurance (from what we've gathered it's best to start using the life insurance money as it is tax free inheritance).

The two questions I have are:
1) What options does my father has with the money from the retirement benefit accounts (401k, 403a, 2x's 457b) in such a way that it keeps growing (annuity, mutual funds, etc, preferably in a tax deferred, non-aggressive way).

2) How to invest this money so that when I inherit (I'm the primary beneficiary) the money such that I minimize taxation on my mothers hard earned money.
<bot>: mother passed away, father inherited $600,000 in qualified money, which I, the only son will inherit. What's the best way for legacy planning in this situation to reduce taxes.