At last and finally are rather similar in meaning as they suggest that we have been waiting for something for a long time. However, at last is normally used only for things that you are pleased have happened whereas finally can be used for both positive and negative things. By the end means at some point before the end.[YSaerTTEW443543]
‘In the end’ means the same as ‘finally’.
The preposition ‘at’ does not work unless you specifiy exactly what something is ‘at the end of’
At the end of the day…
At the end of play…
At the end of the session…