<div class="block">
  <div class="center">center</div>
  <div class="button">button</div>
</div>

.block {
  position: relative;
  display: flex;
  padding: 10px;
  width: 200px;
  justify-content: center;
  text-align: center;
  background-color: gray;
}
.center {
  margin: 70px 0;
  padding: 10px;
  width: 100px;
  background-color: darkgray;
}
.button {
  position: absolute;
  bottom: 10px;
  padding: 10px;
  width: 100px;
  border: 0;
  background-color: darkgray;
  
}