All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Bridal money is the right of a wife upon her husband. Allaah says (which means): {And give the women [upon marriage] their [bridal] gifts graciously.}[Quran 4:4].
If a woman wants to give some money to her husband as a gift to use as bridal money, then it is allowed. Her help to her husband in getting married is a praiseworthy act, and she will be rewarded for it.
Know that facilitating the matter of marriage and lessening its expenditure is a cause of its prosperity. The Prophet said: "In fact, making a woman's proposal easy and her dowry simple blesses the marital life of a woman." [Ahmad]
We draw your attention that the girl before completing the marriage contract is alien to you. So, it is not allowed to have any relation with her, or talk to her except if there is dire necessity and it should be without staying in seclusion.
Allaah Knows best.