Should women give sermons? "Let your women keep silence in the churches: for it is not permitted unto them to speak; but they are commanded to be under obedience, as also saith the law. And if they will learn any thing, let them ask their husbands at home: for it is a shame for women to speak in the church." (1 Corinthians 14:34-35).


Here is another one. 


  "But I suffer not a woman to teach, nor to usurp authority over the man, but to be in silence. For Adam was first formed, then Eve. And Adam was not deceived, but the woman being deceived was in the transgression." (1 Timothy 2:12-14). 


I asked my mom once about this and she explained that when the holy spirit descended, both men and women received it. And this gives us many different gifts such us prophesying, singing and preaching.

I understood her but what I could not ask her was that, Corinthians and Timothy came after the holy spirit descended in Acts. In Africa you cannot keep on asking challenging questions to the elderly as it might be seen as disrespect. Someone help me here.
Your question can be asked using the theological terms of complementarianism and egalitarianism. The crux of the question is this - Did God make all humans the same or did He give each "separate but equal" roles to uniquely fill within the church? 

This, like most real issues of substance, is not one where a single proof verse can answer it. (Although, watch me violate this in a minute!) Rather, one needs to pit the whole of Scripture and discern what the whole of God's heart on the matter is. 

A whole lot of good ink has been shed on this subject, and entire books can only begin to scratch the surface of a fully biblical answer to that question.

For a deeper understanding of the 1 Corinthians 14 passage in particular, this article references Gordon Fee, one of the preeminent experts on how texts should be read. It is a solid summary (albeit 3 long pages) that really should be consulted. Finally, as to the "women should keep silent in church," verse in Corinthians, I have heard it argued that this is actually a return to the subject of Chloe and Scynthe, two women in the church at Corinth who were fighting a lot, but I cannot source this claim. This wiki article also does a good job of summarizing the role of women in the Bible, using these headings. 

The implication of complementarianism would be that women were not created for this role, but rather were to be nurturers rather than leaders. Egalitarians, on the other hand, stress passages like Galatians 3:22 (In Christ there is neither Jew nor Greek, slave nor free, male nor female.)

Biblically speaking, the opening of 2 John makes it difficult for me to say that a "woman should keep silence" in church. After all, it is directly addressed to "the elect lady and her church," which indicates to me that in New Testament times, there were churches in which which women were in charge. 

This said, as a guy, I'll admit, I'm not convinced this is a matter that should divide Christians. It could be one of those "tyranny of the weaker brother" questions, in which the Christian freedom afforded to women could cause others to stumble. Likewise, in churches that have accepted it, keeping women out of the pulpit could be a major stumbling block to those who see this as blantly unfair. 

As Romans 14:5 says,


  Let every man be fully persuaded in his own mind.