score:7
The refusal notice is wonky... The title identifies it as a business visit visa refusal, which is erroneous and unrelated to the application. The content refers to a 'family visa'. There's no such thing as a 'family visa' for visitors or even 'family visit visa'. The ECO refused on paragraph V4.2 (a) (c), but the reasons he wrote indicate he should have refused under V4.2 (e) instead. And the reference to "section 84(1)(c) of the nationality, Immigration and Asylum act 2002" is total whack from the blue. It's old legislation that has been superseded. Normally they are supposed to give at least two reasons, and in your case they gave only one. There could be a missing paragraph that got left out somehow. The sentences starting with "however" and "furthermore" don't make sense. (However to what?) They do not put junior ECO's in Saudi Arabia, so these errors might have been transcription errors by an assistant, or a mix-up in speed codes, or the word processor got confused, or something else. All in all, it's a poor quality refusal notice.
Those errors will not get them to reverse their decision. But it would be advisable to request a different ECO for your next application. They will do this without prejudice if you ask them to; plus an ECM will review the decision if it is adverse to you (normally refusals are randomly sampled).
In comments, you wrote that the salary deposits were in order. So the remaining issue is the provenance of the large deposits. Irregular deposits need to be explained carefully and extra evidence should be submitted to back up your explanation. If the deposits came from your father-in-law's death there would be documentation or correspondence from the estate executor or some other law firm that shows the amounts. You need to find that documentation and include it in your next application (translated to English with an apostille since they will be legal documents).
They usually do not like it when there is a provenance of funds problem because it looks like a 'funds parking' strategy where you are trying to make your financial capacity better than it is. They treat it as mildly deceptive, so you will need to include an explanation of why you did not include the appropriate evidence in your first application.
You wrote in your question that you included hotel bookings as evidence. This reduced the quality of your application because it shows you did not study the guidance. Be sure that your next application is informed by their guidance.
Despite the text in the refusal notice about appeals, there is no path of appeal available to you (they got that part flat-out wrong).
Once you have the necessary evidence, it's fine to apply again.