Student or Learner
Which one of the two usages is correct:-
A and B thank C for his support to the project
A and B thanks C for his support to the project
And what is the reason?
A and B are two people, so 'they thank C' not 'they thanks C'.
The pronoun 'to' does not collocate with 'in' or 'for' in this context.
The reason for the full stop is that no sentence is grammatically correct without a final punctuation mark.
Your appreciation is welcome, burf, but there is no need to write a new post to say thank you. Simply click the Like button on any posts you find helpful. It means that we don't have to open the thread again to read your new post and then find that it doesn't include any new information or an additional question.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.