Need Help Making Money Last

It’s a bit of a long/sad story but especially my mother is going to have somewhere between 200-300k after paying off her house and other things via my step fathers social security after his unfortunate passing. I’m close with my mom and i’m not worried about her blowing through it or anything, but she wants me to help her make it last. Essentially i’m looking for advice on where would be a good / very safe place to invest at least half of it so it can grow but also if needed can be retrieved. any advice is appreciated. she will be getting monthly SS and what not and won’t really need to touch much of it but isn’t good with this stuff. i have some ideas but wanted some more options