You've asked a few questions here, I'll answer each as follows:
how can I prove it for age discrimination? You have to prove a) that you are over 40 years old, b) you were treated adversely, and that you were replaced by a substantially younger employee. If there is no replacement of someone in your position then, you have no claim.
Do I have a case? - This "evidence" is not enough to establish age discrimination. Courts routinely rule that one-time, or stray, comments are not sufficient to establish discrimination.
Didn't pay vacation or severance? Vacation pay and severance are private contractual agreements by employers. There are no laws mandating either. If an employer does not limit vacation to use it or lose it, then it must pay it out by the end of the year. Likewise, there is no law mandating severance.
I believe this answers your question. However, if you need clarification or have follow-up questions regarding this matter, I will be happy to continue our conversation – simply reply to this answer. If you are otherwise satisfied with my response, please leave a positive rating as itis the only way I am able to get credit for my answers. Thank you, ***** ***** wish you all the best with this matter.