Must the female heir reclaim her father's inheritance, represented by his house in Pakistan, despite the dangerous situation and the difficulty of legal conditions there?

The uncle's encroachment upon the inheritance is a major sin, for inheritances are the boundaries set by Allah that may not be transgressed. The uncle has no right to the inheritance in the first place, as he is excluded by the presence of the son.

You have a right to the house, and you must strive with all your might to reclaim it. However, if the situation does not allow for it, and security from the government is lost, and you fear severe harm from your uncle, then you are not obligated to seek its recovery. Rather, you must be patient. You can appoint trustworthy lawyers to recover it through legal means. If you are unable to do so and forgo your right out of fear of excessive harm, then there is no blame upon you.

Defending one's property is permissible but not obligatory. Whoever is subjected to having their property taken by force is allowed to fight in defense of themselves and their property.

Any right you missed out on in this world is an injustice against you by the oppressor, which will benefit you on the Day of Judgment, as their good deeds will be taken in proportion to their injustice, or their evil deeds will be placed upon you.