Restore or replace Grout?

I need to decorate my mum's bathroom in her bungalow as it's become damp due to a failed extractor fan
I'm after some advice on what's best to do with the grout and sealant that has become discoloured.
Is there anything that can be done with the grout in the picture attached or is it best to scrape it out and start again?
If it needs to be removed, what's the best way to go about it?
I also need to clean the shower tray up as well so if anyone has any tips then these would be gratefully received.

Try and bleach spray first on the grout. Leave it for a while and scrub with a stiff brush then rinse. Worth trying that before going to too much trouble

As peanut said use a mixture of 50% bleach 50% water in old spray bottle, best to replace sealant as well after you clean grout.

I used Cif Perfect Shine Mould Remover a couple of months ago on a very similar mouldy shower & it brought it up very well. It needs VERY good ventilation though - I mistakenly left it on several hours, and two weeks later, the bathroom still whiffed. The floor still has a line where I missed spraying it. It's really, really strong.

If the grout is cracked, you'll need to remove it and regrout. Multi tool plus Saxon grout blade, lots of work. Silicone lines wherever there's a chance of movement: wall/tray, corners, etc.

A friend did suggest another alternative for me: covering the tiles with acrylic sheets or bathroom panels. Less cleaning, less work, maybe more expensive initially.
Sadly, even if all the current silicone and grout is miraculously intact, if those are ceramic tiles and the walls weren't tanked (unlikely if done years ago), there could be a lot of damp/rot behind the tiles and tray.

I've used this, spray down wait 20 mins rinse and reapply. Took 6 goes to bring our show up like new.

No need to scrub just make sure you get plenty on.

Don't be dismayed if it doesn't look much different after 1st application it will work!.

I used HG mould spray from b&q which was recommended by a tiler and has worked extremely well. In the past I've found regular bleach/cleaning sprays don't work well but this was great. its about £5 and you leave it on for 20/30 minutes then wash it off. Smells very strong so need to make sure the room has all the windows open!